Specification checklist Every learning outcome in the OCR Chemistry A specification (H432, Version 3.1), numbered as OCR numbers them. Tick what you're confident with; ticks are saved in this browser only. Modules 1 to 4 are the whole of the AS (H032) and are examined again at A level alongside Modules 5 and 6. Paper 1 covers Modules 1, 2, 3 and 5; Paper 2 covers Modules 1, 2, 4 and 6; Paper 3 can draw on all six.
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Module 1: Development of practical skills in chemistry (AS and A level, all papers) 1.2.2 Use of apparatus and techniques questions 1.2.2(a) use of appropriate apparatus to record a range of measurements (to include mass, time, volume of liquids and gases, temperature)1.2.2(b) use of a water bath or electric heater or sand bath for heating1.2.2(c) measurement of pH using pH charts, or pH meter, or pH probe on a data logger1.2.2(d) use of laboratory apparatus for a variety of experimental techniques including:1.2.2(d)(i) titration, using burette and pipette1.2.2(d)(ii) distillation and heating under reflux, including setting up glassware using retort stand and clamps1.2.2(d)(iii) qualitative tests for ions and organic functional groups1.2.2(d)(iv) filtration, including use of fluted filter paper, or filtration under reduced pressure1.2.2(e) use of a volumetric flask, including accurate technique for making up a standard solution1.2.2(f) use of acid– base indicators in titrations of weak/ strong acids with weak/strong alkalis1.2.2(g) purification of:1.2.2(g)(i) a solid product by recrystallisation1.2.2(g)(ii) a liquid product, including use of a separating funnel1.2.2(h) use of melting point apparatus1.2.2(i) use of thin layer or paper chromatography1.2.2(j) setting up of electrochemical cells and measuring voltages1.2.2(k) safely and carefully handling solids and liquids, including corrosive, irritant, flammable and toxic substances1.2.2(l) measurement of rates of reaction by at least two different methods, for example:1.2.2(l)(i) an initial rate method such as a clock reaction1.2.2(l)(ii) a continuous monitoring method. Module 2: Foundations in chemistry (AS and A level, all papers) 2.1.1 Atomic structure and isotopes questions 2.1.1(a) isotopes as atoms of the same element with different numbers of neutrons and different masses2.1.1(b) atomic structure in terms of the numbers of protons, neutrons and electrons for atoms and ions, given the atomic number, mass number and any ionic chargeDifferent models for atomic structure can be used to explain different phenomena, e.g. the Bohr model explains periodic properties. The changing accepted models of atomic structure over time. The use of evidence to accept or reject particular models. 2.1.1(c) explanation of the terms relative isotopic mass (mass compared with 1/12th mass of carbon-12) and relative atomic mass (weighted mean mass compared with 1/12th mass of carbon-12), based on the mass of a12C atom, the standard for atomic massesDefinitions required. 2.1.1(d) use of mass spectrometry in:Knowledge of the mass spectrometer not required. Limited to ions with single charges. 2.1.1(d)(i) the determination of relative isotopic masses and relative abundances of the isotope,Knowledge of the mass spectrometer not required. Limited to ions with single charges. 2.1.1(d)(ii) calculation of the relative atomic mass of an element from the relative abundances of its isotopesKnowledge of the mass spectrometer not required. Limited to ions with single charges. 2.1.1(e) use of the terms relative molecular mass, Mr, and relative formula mass and their calculation from relative atomic masses.For simple molecules, the term relative molecular mass will be used. For compounds with giant structures, the term relative formula mass will be used. Definitions of relative molecular mass and relative formula mass will not be required. 2.1.2 Compounds, formulae and equations questions 2.1.3 Amount of substance questions 2.1.3(a) explanation and use of the terms:Amount of substance will be used in exams using the formula of the substance, e.g. amount of NaCl; amount of O2. In recognition of IUPAC’s review, we will accept both the classical (carbon-12 based) and revised (Avogadro constant based) definitions of the mole in examinations from June 2018 onwards (see https://iupac.org/new-definition-mole-arrived/) The value for NAand the molar gas volume at RTP are provided on the Data Sheet. 2.1.3(a)(i) amount of substanceAmount of substance will be used in exams using the formula of the substance, e.g. amount of NaCl; amount of O2. In recognition of IUPAC’s review, we will accept both the classical (carbon-12 based) and revised (Avogadro constant based) definitions of the mole in examinations from June 2018 onwards (see https://iupac.org/new-definition-mole-arrived/) The value for NAand the molar gas volume at RTP are provided on the Data Sheet. 2.1.3(a)(ii) mole (symbol ‘mol’), as the unit for amount of substanceAmount of substance will be used in exams using the formula of the substance, e.g. amount of NaCl; amount of O2. In recognition of IUPAC’s review, we will accept both the classical (carbon-12 based) and revised (Avogadro constant based) definitions of the mole in examinations from June 2018 onwards (see https://iupac.org/new-definition-mole-arrived/) The value for NAand the molar gas volume at RTP are provided on the Data Sheet. 2.1.3(a)(iii) the Avogadro constant, NA(the number of particles per mole, 6.02 × 1023mol–1)Amount of substance will be used in exams using the formula of the substance, e.g. amount of NaCl; amount of O2. In recognition of IUPAC’s review, we will accept both the classical (carbon-12 based) and revised (Avogadro constant based) definitions of the mole in examinations from June 2018 onwards (see https://iupac.org/new-definition-mole-arrived/) The value for NAand the molar gas volume at RTP are provided on the Data Sheet. 2.1.3(a)(iv) molar mass (mass per mole, units g mol–1),Amount of substance will be used in exams using the formula of the substance, e.g. amount of NaCl; amount of O2. In recognition of IUPAC’s review, we will accept both the classical (carbon-12 based) and revised (Avogadro constant based) definitions of the mole in examinations from June 2018 onwards (see https://iupac.org/new-definition-mole-arrived/) The value for NAand the molar gas volume at RTP are provided on the Data Sheet. 2.1.3(a)(v) molar gas volume (gas volume per mole, units dm3mol–1)Amount of substance will be used in exams using the formula of the substance, e.g. amount of NaCl; amount of O2. In recognition of IUPAC’s review, we will accept both the classical (carbon-12 based) and revised (Avogadro constant based) definitions of the mole in examinations from June 2018 onwards (see https://iupac.org/new-definition-mole-arrived/) The value for NAand the molar gas volume at RTP are provided on the Data Sheet. 2.1.3(b) use of the terms:Definitions not required. 2.1.3(b)(i) empirical formula (the simplest whole number ratio of atoms of each element present in a compound)Definitions not required. 2.1.3(b)(ii) molecular formula (the number and type of atoms of each element in a molecule)Definitions not required. 2.1.3(c) calculations of empirical and molecular formulae, from composition by mass or percentage compositions by mass and relative molecular massTo include calculating empirical formulae from elemental analysis data (see also 6.3.2 e). 2.1.3(d) the terms anhydrous, hydrated and water of crystallisation and calculation of the formula of a hydrated salt from given percentage composition, mass composition or based on experimental results2.1.3(e) calculations, using amount of substance in mol, involving:Learners will be expected to express concentration in mol dm–3and g dm–3. 2.1.3(e)(i) massLearners will be expected to express concentration in mol dm–3and g dm–3. 2.1.3(e)(ii) gas volumeLearners will be expected to express concentration in mol dm–3and g dm–3. 2.1.3(e)(iii) solution volume and concentrationLearners will be expected to express concentration in mol dm–3and g dm–3. 2.1.3(f) the ideal gas equation: pV = nRTThe value for R is provided on the Data Sheet. Learners will be expected to express quantities in SI units. 2.1.3(g) use of stoichiometric relationships in calculations2.1.3(h) calculations to determine:2.1.3(h)(i) the percentage yield of a reaction or related quantities2.1.3(h)(ii) the atom economy of a reaction2.1.3(i) the techniques and procedures required during experiments requiring the measurement of mass, volumes of solutions and gas volumesMany opportunities to carry out experimental and investigative work. 2.1.3(j) the benefits for sustainability of developing chemical processes with a high atom economy.Use of processes with high atom economy in chemical industry and other areas. 2.1.5(a) rules for assigning and calculating oxidation number for atoms in elements, compounds and ionsLearners will be expected to know oxidation numbers of O in peroxides and H in metal hydrides. 2.1.5(b) writing formulae using oxidation numbersAppropriate use of oxidation numbers in written communication. 2.1.5(c) use of a Roman numeral to indicate the magnitude of the oxidation number when an element may have compounds/ions with different oxidation numbersExamples should include, but not be limited to, iron(II) and iron(III). Learners will be expected to write formulae from names such as chlorate(I) and chlorate(III) and vice versa. Note that 'nitrate’ and ‘sulfate’, with no shown oxidation number, are assumed to be NO3– and SO42–. Systematic and unambiguous nomenclature. 2.1.5(d) oxidation and reduction in terms of:Should include examples of s-, p- and d-block elements. 2.1.5(d)(i) electron transferShould include examples of s-, p- and d-block elements. 2.1.5(d)(ii) changes in oxidation numberShould include examples of s-, p- and d-block elements. 2.1.5(e) redox reactions of metals with acids to form salts, including full equations (see also 2.1.4 c)Metals should be from s-, p- and d-blocks e.g. Mg, Al, Fe, Zn. Ionic equations not required. In (e), reactions with acids will be limited to those producing a salt and hydrogen. Reactions involving nitric acid or concentrated sulfuric acid could be assessed in the context of (f). 2.1.5(f) interpretation of redox equations in (e), and unfamiliar redox reactions, to make predictions in terms of oxidation numbers and electron loss/ gain. 2.2.1 Electron structure questions 2.2.1(a) the number of electrons that can fill the first four shells2.2.1(b) atomic orbitals, including:7 Development of models to explain electron structure. 2.2.1(b)(i) as a region around the nucleus that can hold up to two electrons, with opposite spins7 Development of models to explain electron structure. 2.2.1(b)(ii) the shapes of s- and p-orbitals7 Development of models to explain electron structure. 2.2.1(b)(iii) the number of orbitals making up s-, p- and d-sub-shells, and the number of electrons that can fill s-, p- and d-sub-shells7 Development of models to explain electron structure. 2.2.1(c) filling of orbitals:Learners are expected to be familiar with the 'electrons in box' representations. Development of refined models for electron structure. 2.2.1(c)(i) for the first three shells and the 4s and 4p orbitals in order of increasing energyLearners are expected to be familiar with the 'electrons in box' representations. Development of refined models for electron structure. 2.2.1(c)(ii) for orbitals with the same energy, occupation singly before pairingLearners are expected to be familiar with the 'electrons in box' representations. Development of refined models for electron structure. 2.2.1(d) deduction of the electron configurations of:Learners should use sub-shell notation, i.e. for oxygen: 1s22s22p4. 2.2.1(d)(i) atoms, given the atomic number, up to Z = 36Learners should use sub-shell notation, i.e. for oxygen: 1s22s22p4. 2.2.1(d)(ii) ions, given the atomic number and ionic charge, limited to s- and p-blocks up to Z = 36.Learners should use sub-shell notation, i.e. for oxygen: 1s22s22p4. 2.2.2 Bonding and structure questions 2.2.2(a) ionic bonding as electrostatic attraction between positive and negative ions, and the construction of 'dot-and-cross' diagrams2.2.2(b) explanation of the solid structures of giant ionic lattices, resulting from oppositely charged ions strongly attracted in all directions e.g. NaCl2.2.2(c) explanation of the effect of structure and bonding on the physical properties of ionic compounds, including melting and boiling points, solubility and electrical conductivity in solid, liquid and aqueous statesUse of ideas about ionic bonding to explain macroscopic properties. 2.2.2(d) covalent bond as the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms2.2.2(e) construction of ‘dot-and-cross ’ diagrams of molecules and ions to describe:‘Dot-and-cross ’ diagrams of up to six electron pairs (including lone pairs) surrounding a central atom. 2.2.2(e)(i) single covalent bonding‘Dot-and-cross ’ diagrams of up to six electron pairs (including lone pairs) surrounding a central atom. 2.2.2(e)(ii) multiple covalent bonding‘Dot-and-cross ’ diagrams of up to six electron pairs (including lone pairs) surrounding a central atom. 2.2.2(e)(iii) dative covalent (coordinate) bonding‘Dot-and-cross ’ diagrams of up to six electron pairs (including lone pairs) surrounding a central atom. 2.2.2(f) use of the term average bond enthalpy as a measurement of covalent bond strengthLearners should appreciate that the larger the value of the average bond enthalpy, the stronger the covalent bond. Definition and calculations not required. Average bond enthalpies and related calculations are covered in detail in 3.2.1 f. 2.2.2(g) the shapes of, and bond angles in, molecules and ions with up to six electron pairs (including lone pairs) surrounding the central atom as predicted by electron pair repulsion, including the relative repulsive strengths of bonded pairs and lone pairs of electronsillustrate shapes of molecules and ions. 2 Using electron pair repulsion theory to predict molecular shapes. 2.2.2(h) electron pair repulsion to explain the following shapes of molecules and ions: linear, non-linear, trigonal planar, pyramidal, tetrahedral and octahedralLearners are expected to know that lone pairs repel more than bonded pairs and the bond angles for common examples of each shape including CH4(109.5°), NH3(107°) and H2O (104.5°). 2.2.2(i) electronegativity as the ability of an atom to attract the bonding electrons in a covalent bond; interpretation of Pauling electronegativity valuesLearners should be aware that electronegativity increases towards F in the periodic table. 2 Using ideas about electronegativity to predict chemical bond type. 2.2.2(j) explanation of:A polar molecule requires polar bonds with dipoles that do not cancel due to their direction. E.g. H2O and CO2both have polar bonds but only H2O has an overall dipole. 2.2.2(j)(i) a polar bond and permanent dipole within molecules containing covalently-bonded atoms with different electronegativitiesA polar molecule requires polar bonds with dipoles that do not cancel due to their direction. E.g. H2O and CO2both have polar bonds but only H2O has an overall dipole. 2.2.2(j)(ii) a polar molecule and overall dipole in terms of permanent dipole(s) and molecular shapeA polar molecule requires polar bonds with dipoles that do not cancel due to their direction. E.g. H2O and CO2both have polar bonds but only H2O has an overall dipole. 2.2.2(k) intermolecular forces based on permanent dipole– dipole interactions and induced dipole– dipole interactionsPermanent dipole– dipole and induced dipole– dipole interactions can both be referred to as van der Waals’ forces. Induced dipole– dipole interactions can also be referred to as London (dispersion) forces. 2 Dipole interactions as a model to explain intermolecular bonding. 2.2.2(l) hydrogen bonding as intermolecular bonding between molecules containing N, O or F and the H atom of –NH, –OH or HFIncluding the role of lone pairs. 2.2.2(m) explanation of anomalous properties of H2O resulting from hydrogen bonding, e.g.:Use of ideas about hydrogen bonding to explain macroscopic properties. 2.2.2(m)(i) the density of ice compared with waterUse of ideas about hydrogen bonding to explain macroscopic properties. 2.2.2(m)(ii) its relatively high melting and boiling pointsUse of ideas about hydrogen bonding to explain macroscopic properties. 2.2.2(n) explanation of the solid structures of simple molecular lattices, as covalently bonded molecules attracted by intermolecular forces, e.g. I2, ice2.2.2(o) explanation of the effect of structure and bonding on the physical properties of covalent compounds with simple molecular lattice structures including melting and boiling points, solubility and electrical conductivity. Module 3: Periodic table and energy (AS and A level; A-level Papers 1 and 3) 3.1.1(a) the periodic table as the arrangement of elements:7,11 The development of the Periodic Law and acceptance by the scientific community. 11 The extension of the periodic table through discovery and confirmation of new elements. 3.1.1(a)(i) by increasing atomic (proton) number7,11 The development of the Periodic Law and acceptance by the scientific community. 11 The extension of the periodic table through discovery and confirmation of new elements. 3.1.1(a)(ii) in periods showing repeating trends in physical and chemical properties (periodicity)7,11 The development of the Periodic Law and acceptance by the scientific community. 11 The extension of the periodic table through discovery and confirmation of new elements. 3.1.1(a)(iii) in groups having similar chemical properties7,11 The development of the Periodic Law and acceptance by the scientific community. 11 The extension of the periodic table through discovery and confirmation of new elements. 3.1.1(b)(i) the periodic trend in electron configurations across Periods 2 and 3 (see also 2.2.1 d)3.1.1(b)(ii) classification of elements into s-, p- and d-blocks3.1.1(c) first ionisation energy (removal of 1 mol of electrons from 1 mol of gaseous atoms) and successive ionisation energy, and:Definition required for first ionisation energy only. Explanation to include the small decreases as a result of s- and p-sub-shell energies (e.g. between Be and B) and p-orbital repulsion (e.g. between N and O). 2 Trends in ionisation energy support the Bohr model of the atom. 3.1.1(c)(i) explanation of the trend in first ionisation energies across Periods 2 and 3, and down a group, in terms of attraction, nuclear charge and atomic radiusDefinition required for first ionisation energy only. Explanation to include the small decreases as a result of s- and p-sub-shell energies (e.g. between Be and B) and p-orbital repulsion (e.g. between N and O). 2 Trends in ionisation energy support the Bohr model of the atom. 3.1.1(c)(ii) prediction from successive ionisation energies of the number of electrons in each shell of an atom and the group of an elementDefinition required for first ionisation energy only. Explanation to include the small decreases as a result of s- and p-sub-shell energies (e.g. between Be and B) and p-orbital repulsion (e.g. between N and O). 2 Trends in ionisation energy support the Bohr model of the atom. 3.1.1(d) explanation of:No details of cubic or hexagonal packing required. 3.1.1(d)(i) metallic bonding as strong electrostatic attraction between cations (positive ions) and delocalised electronsNo details of cubic or hexagonal packing required. 3.1.1(d)(ii) a giant metallic lattice structure, e.g. all metalsNo details of cubic or hexagonal packing required. 3.1.1(e) explanation of the solid giant covalent lattices of carbon (diamond, graphite and graphene) and silicon as networks of atoms bonded by strong covalent bonds9 Use of ideas about bonding to explain the strength and conductive properties of graphene, and its potential applications and benefits. 3.1.1(f) explanation of physical properties of giant metallic and giant covalent lattices, including melting and boiling points, solubility and electrical conductivity in terms of structure and bondingExplanations should be in terms of the types of particle present in a lattice, the relative strength of forces and bonds, and the mobility of the particles involved, as appropriate. Use of ideas about bonding to explain macroscopic properties. 3.1.1(g) explanation of the variation in melting points across Periods 2 and 3 in terms of structure and bonding (see also 2.2.2 o).Trend in structure from giant metallic to giant covalent to simple molecular lattice. 3.1.3 The halogens questions 3.1.3(a) existence of halogens as diatomic molecules and explanation of the trend in the boiling points of Cl2, Br2and I2, in terms of induced dipole– dipole interactions (London forces) (see also 2.2.2 k)3.1.3(b) the outer shell s2p5electron configuration and the gaining of one electron in many redox reactions to form 1– ionsThroughout this section, explanations of redox reactions should emphasise electron transfer and oxidation number changes and include full and ionic equations (see also 2.1.5 Redox). 3.1.3(c) the trend in reactivity of the halogens Cl2, Br2 and I2, illustrated by reaction with other halide ionsIncluding colour change in aqueous and organic solutions. 3.1.3(d) explanation of the trend in reactivity shown in (c), from the decreasing ease of forming 1– ions, in terms of attraction, atomic radius and electron shielding3.1.3(e) explanation of the term disproportionation as oxidation and reduction of the same element, illustrated by:3.1.3(e)(i) the reaction of chlorine with water as used in water treatment3.1.3(e)(ii) the reaction of chlorine with cold, dilute aqueous sodium hydroxide, as used to form bleach3.1.3(e)(iii) reactions analogous to those specified in (i) and (ii)3.1.3(f) the benefits of chlorine use in water treatment (killing bacteria) contrasted with associated risks (e.g. hazards of toxic chlorine gas and possible risks from formation of chlorinated hydrocarbons)10,12 Decisions on whether or not to chlorinate water depend on balance of benefits and risks, and ethical considerations of people’s right to choose. Consideration of other methods of purifying drinking water. 3.1.3(g) the precipitation reactions, including ionic equations, of the aqueous anions Cl–, Br– and I– with aqueous silver ions, followed by aqueous ammonia, and their use as a test for different halide ions.Complexes with ammonia are not required other than observations. (see also 3.1.4 a) Qualitative analysis. 3.2.1 Enthalpy changes questions 3.2.1(a) explanation that some chemical reactions are accompanied by enthalpy changes that are exothermic (∆H, negative) or endothermic (∆H, positive)3.2.1(b) construction of enthalpy profile diagrams to show the difference in the enthalpy of reactants compared with products3.2.1(c) qualitative explanation of the term activation energy, including use of enthalpy profile diagramsActivation energy in terms of the minimum energy required for a reaction to take place. 3.2.1(d) explanation and use of the terms:Definitions required for enthalpy changes of formation, combustion and neutralisation only. Standard conditions can be considered as 100 kPa and a stated temperature, 298 K. 3.2.1(d)(i) standard conditions and standard states (physical states under standard conditions)Definitions required for enthalpy changes of formation, combustion and neutralisation only. Standard conditions can be considered as 100 kPa and a stated temperature, 298 K. 3.2.1(d)(ii) enthalpy change of reaction (enthalpy change associated with a stated equation, ∆rH)Definitions required for enthalpy changes of formation, combustion and neutralisation only. Standard conditions can be considered as 100 kPa and a stated temperature, 298 K. 3.2.1(d)(iii) enthalpy change of formation (formation of 1 mol of a compound from its elements, ∆fH)Definitions required for enthalpy changes of formation, combustion and neutralisation only. Standard conditions can be considered as 100 kPa and a stated temperature, 298 K. 3.2.1(d)(iv) enthalpy change of combustion (complete combustion of 1 mol of a substance, ∆cH)Definitions required for enthalpy changes of formation, combustion and neutralisation only. Standard conditions can be considered as 100 kPa and a stated temperature, 298 K. 3.2.1(d)(v) enthalpy change of neutralisation (formation of 1 mol of water from neutralisation, ∆neutH)Definitions required for enthalpy changes of formation, combustion and neutralisation only. Standard conditions can be considered as 100 kPa and a stated temperature, 298 K. 3.2.1(e) determination of enthalpy changes directly from appropriate experimental results, including use of the relationship: q = mc∆T3.2.1(f)(i) explanation of the term average bond enthalpy (as the breaking of 1 mol of bonds in gaseous molecules)Formal definition of average bond enthalpy not required. Learners are expected to understand that an actual bond enthalpy may differ from the average value. 3.2.1(f)(ii) explanation of exothermic and endothermic reactions in terms of enthalpy changes associated with the breaking and making of chemical bondsFormal definition of average bond enthalpy not required. Learners are expected to understand that an actual bond enthalpy may differ from the average value. 3.2.1(f)(iii) use of average bond enthalpies to calculate enthalpy changes and related quantities (see also 2.2.2 f)Formal definition of average bond enthalpy not required. Learners are expected to understand that an actual bond enthalpy may differ from the average value. 3.2.1(g) Hess’ law for construction of enthalpy cycles and calculations to determine indirectly:Definition of Hess’ law not required. Unfamiliar enthalpy cycles will be provided. Application of the principle of conservation of energy to determine enthalpy changes. 3.2.1(g)(i) an enthalpy change of reaction from enthalpy changes of combustionDefinition of Hess’ law not required. Unfamiliar enthalpy cycles will be provided. Application of the principle of conservation of energy to determine enthalpy changes. 3.2.1(g)(ii) an enthalpy change of reaction from enthalpy changes of formationDefinition of Hess’ law not required. Unfamiliar enthalpy cycles will be provided. Application of the principle of conservation of energy to determine enthalpy changes. 3.2.1(g)(iii) enthalpy changes from unfamiliar enthalpy cyclesDefinition of Hess’ law not required. Unfamiliar enthalpy cycles will be provided. Application of the principle of conservation of energy to determine enthalpy changes. 3.2.1(h) the techniques and procedures used to determine enthalpy changes directly and indirectly.To include the enthalpy changes covered in 5.2.1 c. Opportunities for carrying out experimental and investigative work. 3.2.2 Reaction rates questions 3.2.2(a) the effect of concentration, including the pressure of gases, on the rate of a reaction, in terms of frequency of collisions3.2.2(b) calculation of reaction rate from the gradients of graphs measuring how a physical quantity changes with timeSuitable physical quantities to monitor could include concentration, gas volume, mass, etc. 3.2.2(c) explanation of the role of a catalyst:Details of processes are not required. 3.2.2(c)(i) in increasing reaction rate without being used up by the overall reactionDetails of processes are not required. 3.2.2(c)(ii) in allowing a reaction to proceed via a different route with lower activation energy, as shown by enthalpy profile diagramsDetails of processes are not required. 3.2.2(d)(i) explanation of the terms homogeneous and heterogeneous catalysts10 Benefits to the environment of improved sustainability weighed against toxicity of some catalysts. 3.2.2(d)(ii) explanation that catalysts have great economic importance and benefits for increased sustainability by lowering temperatures and reducing energy demand from combustion of fossil fuels with resulting reduction in CO2emissions10 Benefits to the environment of improved sustainability weighed against toxicity of some catalysts. 3.2.2(e) the techniques and procedures used to investigate reaction rates including the measurement of mass, gas volumes and timeMany opportunities to carry out experimental and investigative work. 3.2.2(f) qualitative explanation of the Boltzmann distribution and its relationship with activation energy (see also 3.2.1 c)3.2.2(g) explanation, using Boltzmann distributions, of the qualitative effect on the proportion of molecules exceeding the activation energy and hence the reaction rate, for:2,5 Use of Boltzmann distribution model to explain effect on reaction rates. 3.2.2(g)(i) temperature changes2,5 Use of Boltzmann distribution model to explain effect on reaction rates. 3.2.2(g)(ii) catalytic behaviour (see also 3.2.2 c).2,5 Use of Boltzmann distribution model to explain effect on reaction rates. Module 4: Core organic chemistry (AS and A level; A-level Papers 2 and 3) 4.1.1 Basic concepts of organic chemistry questions 4.1.1(a) application of IUPAC rules of nomenclature for systematically naming organic compoundsNomenclature will be limited to the functional groups within this specification. E.g. CH3CH2CH(CH3)CH2OH has the systematic name: 2-methylbutan-1-ol. Learners will be expected to know the names of the first ten members of the alkanes homologous series and their corresponding alkyl groups. Use of systematic nomenclature to avoid ambiguity. The role of IUPAC in developing a systematic framework for chemical nomenclature. 4.1.1(b) interpretation and use of the terms:See also 2.1.3 b for empirical formula and molecular formula. Definitions not required. In structural formulae, the carboxyl group will be represented as COOH and the ester group as COO. The symbols below will be used for cyclohexane and benzene: Communication using organic chemical structures; selecting the appropriate type of formula for the context. 4.1.1(b)(i) general formula (the simplest algebraic formula of a member of a homologous series) e.g. for an alkane: CnH2n+2See also 2.1.3 b for empirical formula and molecular formula. Definitions not required. In structural formulae, the carboxyl group will be represented as COOH and the ester group as COO. The symbols below will be used for cyclohexane and benzene: Communication using organic chemical structures; selecting the appropriate type of formula for the context. 4.1.1(b)(ii) structural formula (the minimal detail that shows the arrangement of atoms in a molecule) e.g. for butane: CH3CH2CH2CH3or CH3(CH2)2CH3See also 2.1.3 b for empirical formula and molecular formula. Definitions not required. In structural formulae, the carboxyl group will be represented as COOH and the ester group as COO. The symbols below will be used for cyclohexane and benzene: Communication using organic chemical structures; selecting the appropriate type of formula for the context. 4.1.1(b)(iii) displayed formula (the relative positioning of atoms and the bonds between them) e.g. for ethanol: H H H C C O H H HSee also 2.1.3 b for empirical formula and molecular formula. Definitions not required. In structural formulae, the carboxyl group will be represented as COOH and the ester group as COO. The symbols below will be used for cyclohexane and benzene: Communication using organic chemical structures; selecting the appropriate type of formula for the context. 4.1.1(b)(iv) skeletal formula (the simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups) e.g. for butan-2-ol: OHSee also 2.1.3 b for empirical formula and molecular formula. Definitions not required. In structural formulae, the carboxyl group will be represented as COOH and the ester group as COO. The symbols below will be used for cyclohexane and benzene: Communication using organic chemical structures; selecting the appropriate type of formula for the context. 4.1.1(c) interpretation and use of the terms:Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(c)(i) homologous series (a series of organic compounds having the same functional group but with each successive member differing by CH2)Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(c)(ii) functional group (a group of atoms responsible for the characteristic reactions of a compound)Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(c)(iii) alkyl group (of formula CnH2n+1)Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(c)(iv) aliphatic (a compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings)Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(c)(v) alicyclic (an aliphatic compound arranged in non-aromatic rings with or without side chains)Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(c)(vi) aromatic (a compound containing a benzene ring)Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(c)(vii) saturated (single carbon– carbon bonds only) and unsaturated (the presence of multiple carbon– carbon bonds, including C=C, C/C and aromatic rings)Definition required for homologous series only. R may be used to represent alkyl groups, but also other fragments of organic compounds not involved in reactions. The terms saturated and unsaturated will be used to indicate the presence of multiple carbon– carbon bonds as distinct from the wider term ‘degree of saturation’ used also for any multiple bonds and cyclic compounds. 4.1.1(d) use of the general formula of a homologous series to predict the formula of any member of the series4.1.1(e) explanation of the term structural isomers (compounds with the same molecular formula but different structural formulae) and determination of possible structural formulae of an organic molecule, given its molecular formula4.1.1(f) the different types of covalent bond fission:4.1.1(f)(i) homolytic fission (in terms of each bonding atom receiving one electron from the bonded pair, forming two radicals)4.1.1(f)(ii) heterolytic fission (in terms of one bonding atom receiving both electrons from the bonded pair)4.1.1(g) the term radical (a species with an unpaired electron) and use of ‘dots’ to represent species that are radicals in mechanismsRadical mechanisms will be represented by a sequence of equations. Dots, •, are required in all instances where there is a single unpaired electron (e.g. Cl• and CH3•). Dots are not required for species that are diradicals (e.g. O). 4.1.1(h) a ‘curly arrow’ described as the movement of an electron pair, showing either heterolytic fission or formation of a covalent bond‘Half curly arrows’ are not required, see 4.1.2 f. 8 Use of the ‘curly arrow’ model to demonstrate electron flow in organic reactions. 4.1.1(i) reaction mechanisms, using diagrams, to show clearly the movement of an electron pair with ‘curly arrows’ and relevant dipoles.Any relevant dipoles should be included. Curly arrows should start from a bond, a lone pair of electrons or a negative charge. 2,8 Use of reaction mechanisms to explain organic reactions. 4.1.3(a) alkenes as unsaturated hydrocarbons containing a C=C bond comprising a π-bond (sideways overlap of adjacent p-orbitals above and below the bonding C atoms) and a σ-bond (overlap of orbitals directly between the bonding atoms) (see also 4.1.2 a); restricted rotation of the π-bondHybridisation is not required. Use of the model of orbital overlap to explain covalent bonding in organic compounds. 4.1.3(b) explanation of the trigonal planar shape and bond angle around each carbon in the C=C of alkenes in terms of electron pair repulsion (see also 2.2.2 g– h, 4.1.2 b)4.1.3(c)(i) explanation of the terms: • stereoisomers (compounds with the same structural formula but with a different arrangement in space) • E/Z isomerism (an example of stereoisomerism, in terms of restricted rotation about a double bond and the requirement for two different groups to be attached to each carbon atom of the C=C group) • cis– trans isomerism (a special case of E/Z isomerism in which two of the substituent groups attached to each carbon atom of the C=C group are the same)H3C H H H C C C C H CH CH 3 H3C3 E-but-2-ene Z-but-2-ene (trans) (cis) Use of E as equivalent to trans and Z as equivalent to cis is only consistently correct when there is an H on each carbon atom of the C=C bond. Assigning CIP priorities to double or triple bonds within R groups is not required: R R" C C R' R''' 4.1.3(c)(ii) use of Cahn–Ingold–Prelog (CIP) priority rules to identify the E and Z stereoisomersH3C H H H C C C C H CH CH 3 H3C3 E-but-2-ene Z-but-2-ene (trans) (cis) Use of E as equivalent to trans and Z as equivalent to cis is only consistently correct when there is an H on each carbon atom of the C=C bond. Assigning CIP priorities to double or triple bonds within R groups is not required: R R" C C R' R''' 4.1.3(d) determination of possible E/Z or cis– trans stereoisomers of an organic molecule, given its structural formula4.1.3(e) the reactivity of alkenes in terms of the relatively low bond enthalpy of the π-bond4.1.3(f) addition reactions of alkenes with:(see also 6.3.1 c) 4.1.3(f)(i) hydrogen in the presence of a suitable catalyst, e.g. Ni, to form alkanes(see also 6.3.1 c) 4.1.3(f)(ii) halogens to form dihaloalkanes, including the use of bromine to detect the presence of a double C=C bond as a test for unsaturation in a carbon chain(see also 6.3.1 c) 4.1.3(f)(iii) hydrogen halides to form haloalkanes(see also 6.3.1 c) 4.1.3(f)(iv) steam in the presence of an acid catalyst, e.g. H3PO4, to form alcohols(see also 6.3.1 c) 4.1.3(g) definition and use of the term electrophile (an electron pair acceptor)4.1.3(h) the mechanism of electrophilic addition in alkenes by heterolytic fission (see also 4.1.1 h– i)For the reaction with halogens, either a carbocation or a halonium ion intermediate is acceptable. 2,8 Use of reaction mechanisms to explain organic reactions. 4.1.3(i) use of Markownikoff’s rule to predict formation of a major organic product in addition reactions of H–X to unsymmetrical alkenes, e.g. H–Br to propene, in terms of the relative stabilities of carbocation intermediates in the mechanismLimited to stabilities of primary, secondary and tertiary carbocations. Explanation for relative stabilities of carbocations not required. 2,5 Use of stability to explain products of organic reactions. 4.1.3(j) addition polymerisation of alkenes and substituted alkenes, including:4.1.3(j)(i) the repeat unit of an addition polymer deduced from a given monomer4.1.3(j)(ii) identification of the monomer that would produce a given section of an addition polymer4.1.3(k) the benefits for sustainability of processing waste polymers by:10 Benefits of cheap oil-derived plastics counteracted by problems for the environment of landfill; the move to re-using waste, improving the use of resources. 4.1.3(k)(i) combustion for energy production10 Benefits of cheap oil-derived plastics counteracted by problems for the environment of landfill; the move to re-using waste, improving the use of resources. 4.1.3(k)(ii) use as an organic feedstock for the production of plastics and other organic chemicals10 Benefits of cheap oil-derived plastics counteracted by problems for the environment of landfill; the move to re-using waste, improving the use of resources. 4.1.3(k)(iii) removal of toxic waste products, e.g. removal of HCl formed during disposal by combustion of halogenated plastics (e.g. PVC)10 Benefits of cheap oil-derived plastics counteracted by problems for the environment of landfill; the move to re-using waste, improving the use of resources. 4.1.3(l) the benefits to the environment of development of biodegradable and photodegradable polymers.10 Benefits of reduced dependency on finite resources and alleviating problems from disposal of persistent plastic waste. 4.2.2(a) hydrolysis of haloalkanes in a substitution reaction:(see also 6.3.1 c) 4.2.2(a)(i) by aqueous alkali(see also 6.3.1 c) 4.2.2(a)(ii) by water in the presence of AgNO3and ethanol to compare experimentally the rates of hydrolysis of different carbon– halogen bonds(see also 6.3.1 c) 4.2.2(b) definition and use of the term nucleophile (an electron pair donor)4.2.2(c) the mechanism of nucleophilic substitution in the hydrolysis of primary haloalkanes with aqueous alkali (see also 4.1.1 h– i)2 Use of reaction mechanisms to explain organic reactions. 4.2.2(d) explanation of the trend in the rates of hydrolysis of primary haloalkanes in terms of the bond enthalpies of carbon– halogen bonds (C–F, C–Cl, C–Br and C–I)4.2.2(e) production of halogen radicals by the action of ultraviolet (UV) radiation on CFCs in the upper atmosphere and the resulting catalysed breakdown of the Earth’s protective ozone layer, including equations to represent:Simple equations of the breakdown process are required, e.g. CF2Cl2 → CF2Cl • + •Cl •Cl + O3 → •C lO + O2 •Cl O + O → •C l + O2 Learners could be expected to construct similar equations for other stated radicals. 10,11,12 Benefits of CFCs; acceptance of scientific evidence explaining ozone depletion leading to government legislation against CFC use. 4.2.2(e)(i) the production of halogen radicalsSimple equations of the breakdown process are required, e.g. CF2Cl2 → CF2Cl • + •Cl •Cl + O3 → •C lO + O2 •Cl O + O → •C l + O2 Learners could be expected to construct similar equations for other stated radicals. 10,11,12 Benefits of CFCs; acceptance of scientific evidence explaining ozone depletion leading to government legislation against CFC use. 4.2.2(e)(ii) the catalysed breakdown of ozone by Cl • and other radicals e.g. •NO.Simple equations of the breakdown process are required, e.g. CF2Cl2 → CF2Cl • + •Cl •Cl + O3 → •C lO + O2 •Cl O + O → •C l + O2 Learners could be expected to construct similar equations for other stated radicals. 10,11,12 Benefits of CFCs; acceptance of scientific evidence explaining ozone depletion leading to government legislation against CFC use. 4.2.4 Analytical techniques questions 4.2.4(a) infrared (IR) radiation causes covalent bonds to vibrate more and absorb energy4.2.4(b) absorption of infrared radiation by atmospheric gases containing C=O, O–H and C–H bonds (e.g. CO2, H2O and CH4), the suspected link to global warming and resulting changes to energy usage10,11,12 Acceptance of scientific evidence explaining global warming has prompted governments towards policies to use renewable energy supplies. 4.2.4(c) use of an infrared spectrum of an organic compound to identify:In examinations, infrared absorption data will be provided on the Data Sheet. Learners should be aware that most organic compounds produce a peak at approximately 3000 cm–1due to absorption by C–H bonds. 4.2.4(c)(i) an alcohol from an absorption peak of the O–H bondIn examinations, infrared absorption data will be provided on the Data Sheet. Learners should be aware that most organic compounds produce a peak at approximately 3000 cm–1due to absorption by C–H bonds. 4.2.4(c)(ii) an aldehyde or ketone from an absorption peak of the C=O bondIn examinations, infrared absorption data will be provided on the Data Sheet. Learners should be aware that most organic compounds produce a peak at approximately 3000 cm–1due to absorption by C–H bonds. 4.2.4(c)(iii) a carboxylic acid from an absorption peak of the C=O bond and a broad absorption peak of the O–H bondIn examinations, infrared absorption data will be provided on the Data Sheet. Learners should be aware that most organic compounds produce a peak at approximately 3000 cm–1due to absorption by C–H bonds. 4.2.4(d) interpretations and predictions of an infrared spectrum of familiar or unfamiliar substances using supplied dataRestricted to functional groups studied in this specification (see also 6.3.2 e). 5 Analysis and interpretation of spectra. 4.2.4(e) use of infrared spectroscopy to monitor gases causing air pollution (e.g. CO and NO from car emissions) and in modern breathalysers to measure ethanol in the breathUse of analytical techniques to provide evidence for law courts, e.g. drink driving. 4.2.4(f) use of a mass spectrum of an organic compound to identify the molecular ion peak and hence to determine molecular massLimited to ions with single charges. Learners will not be expected to interpret mass spectra of organic halogen compounds. Limited to organic compounds encountered in this specification (see also 6.3.2 e). Learners should be aware that mass spectra may contain a small M+1 peak from the small proportion of carbon-13. 5 Analysis and interpretation of spectra. 4.2.4(g) analysis of fragmentation peaks in a mass spectrum to identify parts of structures.fragment ions. 5 Analysis and interpretation of spectra. 4.2.4(h) deduction of the structures of organic compounds from different analytical data including:Limited to functional groups encountered in this specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Analysis and interpretation of different analytical data. 4.2.4(h)(i) elemental analysis (see also 2.1.3c)Limited to functional groups encountered in this specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Analysis and interpretation of different analytical data. 4.2.4(h)(ii) mass spectraLimited to functional groups encountered in this specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Analysis and interpretation of different analytical data. 4.2.4(h)(iii) IR spectra.Limited to functional groups encountered in this specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Analysis and interpretation of different analytical data. Module 5: Physical chemistry and transition elements (A level only; Papers 1 and 3) 5.1.1(a) explanation and use of the terms: rate of reaction, order, overall order, rate constant, half- life, rate-determining step5.1.1(b) deduction of:Learners are expected to interpret initial rates data to determine orders with respect to reactants. Integrated forms of rate equations are not required. Use of rate equations. 5.1.1(b)(i) orders from experimental dataLearners are expected to interpret initial rates data to determine orders with respect to reactants. Integrated forms of rate equations are not required. Use of rate equations. 5.1.1(b)(ii) a rate equation from orders of the form: rate = k[A]m[B]n, where m and n are 0, 1 or 2Learners are expected to interpret initial rates data to determine orders with respect to reactants. Integrated forms of rate equations are not required. Use of rate equations. 5.1.1(c) calculation of the rate constant, k, and related quantities, from a rate equation including determination of units5.1.1(d) from a concentration– time graph:Concentration– time graphs can be plotted from continuous measurements taken during the course of a reaction (continuous monitoring). 5.1.1(d)(i) deduction of the order (0 or 1) with respect to a reactant from the shape of the graphConcentration– time graphs can be plotted from continuous measurements taken during the course of a reaction (continuous monitoring). 5.1.1(d)(ii) calculation of reaction rates from the measurement of gradients (see also 3.2.2 b)Concentration– time graphs can be plotted from continuous measurements taken during the course of a reaction (continuous monitoring). 5.1.1(e) from a concentration– time graph of a first order reaction, measurement of constant half-life, t1/2Learners should be aware of the constancy of half- life for a first order reaction. 5.1.1(f) for a first order reaction, determination of the rate constant, k, from the constant half-life, t1/2, using the relationship: k = ln 2/ t1/2Learners will not be required to derive this equation from the exponential relationship between concentration and time, [A] = [A0]e– kt. 5.1.1(g) from a rate– concentration graph:Rate– concentration data can be obtained from initial rates investigations of separate experiments using different concentrations of one of the reactants. Clock reactions are an approximation of this method where the time measured is such that the reaction has not proceeded too far. Link between order and rate. 5.1.1(g)(i) deduction of the order (0, 1 or 2) with respect to a reactant from the shape of the graphRate– concentration data can be obtained from initial rates investigations of separate experiments using different concentrations of one of the reactants. Clock reactions are an approximation of this method where the time measured is such that the reaction has not proceeded too far. Link between order and rate. 5.1.1(g)(ii) determination of rate constant for a first order reaction from the gradientRate– concentration data can be obtained from initial rates investigations of separate experiments using different concentrations of one of the reactants. Clock reactions are an approximation of this method where the time measured is such that the reaction has not proceeded too far. Link between order and rate. 5.1.1(h) the techniques and procedures used to investigate reaction rates by the initial rates method and by continuous monitoring, including use of colorimetry (see also 3.2.2 e)10 Opportunities to carry out experimental and investigative work. 5.1.1(i) for a multi-step reaction, prediction of,Use of experimental evidence for the proposal of reaction mechanisms. 5.1.1(i)(i) a rate equation that is consistent with the rate-determining stepUse of experimental evidence for the proposal of reaction mechanisms. 5.1.1(i)(ii) possible steps in a reaction mechanism from the rate equation and the balanced equation for the overall reactionUse of experimental evidence for the proposal of reaction mechanisms. 5.1.1(j) a qualitative explanation of the effect of temperature change on the rate of a reaction and hence the rate constant (see 3.2.2 f– g)5.1.1(k) the Arrhenius equation:Ea= activation energy, A = pre-exponential factor, R = gas constant (provided on the Data Sheet) Explanation of A is not required. Equations provided on the Data Sheet. Link between k and T. 5.1.1(k)(i) the exponential relationship between the rate constant, k and temperature, T given by the Arrhenius equation, k = Ae–Ea/RTEa= activation energy, A = pre-exponential factor, R = gas constant (provided on the Data Sheet) Explanation of A is not required. Equations provided on the Data Sheet. Link between k and T. 5.1.1(k)(ii) determination of Eaand A graphically using: ln k = – Ea/RT + ln A derived from the Arrhenius equation.Ea= activation energy, A = pre-exponential factor, R = gas constant (provided on the Data Sheet) Explanation of A is not required. Equations provided on the Data Sheet. Link between k and T. 5.1.3 Acids, bases and buffers questions 5.1.3(a)(i) a Brønsted–Lowry acid as a species that donates a proton and a Brønsted–Lowry base as a species that accepts a proton (see also 2.1.4 Acids)in equations for acid– base equilibria. 7 Development of different models over time to explain acid– base behaviour. 5.1.3(a)(ii) use of the term conjugate acid– base pairsin equations for acid– base equilibria. 7 Development of different models over time to explain acid– base behaviour. 5.1.3(a)(iii) monobasic, dibasic and tribasic acidsin equations for acid– base equilibria. 7 Development of different models over time to explain acid– base behaviour. 5.1.3(b) the role of H+ in the reactions of acids with metals and bases (including carbonates, metal oxides and alkalis), using ionic equations (see also 2.1.4 c, 2.1.5 e)5.1.3(c)(i) the acid dissociation constant, Ka, for the extent of acid dissociation (see also 2.1.4 b)5.1.3(c)(ii) the relationship between Kaand p Ka5.1.3(d) use of the expression for pH as: pH = – log[H+] [H+] = 10– pHpH as convenient terminology for communicating [H+]. 5.1.3(e) use of the expression for the ionic product of water, Kw5.1.3(f) calculations of pH, or related quantities, for:5.1.3(f)(i) strong monobasic acids5.1.3(f)(ii) strong bases, using Kw5.1.3(g) calculations of pH, Kaor related quantities, for a weak monobasic acid using approximationsApproximations for weak acid calculations: [HA]equilibrium~ [HA]undissociated i.e. [HA] >> [H+] [H+]equilibrium~ [A–]equilibrium i.e. negligible dissociation of H2O. Learners will not be required to solve quadratic equations. 5.1.3(h) limitations of using approximations to Karelated calculations for ‘stronger’ weak acidsIncluding reasons why [HA]equilibrium~ [HA]undissociatedmay no longer be valid. Understanding of the circumstances under which Kaapproximations break down. 5.1.3(i) a buffer solution as a system that minimises pH changes on addition of small amounts of an acid or a base5.1.3(j) formation of a buffer solution from:5.1.3(j)(i) a weak acid and a salt of the weak acid, e.g. CH3COOH/CH3COONa5.1.3(j)(ii) excess of a weak acid and a strong alkali, e.g. excess CH3COOH/NaOH5.1.3(k) explanation of the role of the conjugate acid– base pair in an acid buffer solution, e.g. CH3COOH/CH3COO–, in the control of pH5.1.3(l) calculation of the pH of a buffer solution, from the Kavalue of a weak acid and the equilibrium concentrations of the conjugate acid– base pair; calculations of related quantities5.1.3(m) explanation of the control of blood pH by the carbonic acid– hydrogencarbonate buffer systemThe H2CO3/HCO3– buffer is present in blood plasma, maintaining a pH between 7.35 and 7.45. 5.1.3(n) pH titration curves for combinations of strong and weak acids with strong and weak bases, including:No indicator is suitable for a weak acid/weak base titration. The indicator should be considered as a weak acid, HA. 5.1.3(n)(i) sketch and interpretation of their shapesNo indicator is suitable for a weak acid/weak base titration. The indicator should be considered as a weak acid, HA. 5.1.3(n)(ii) explanation of the choice of suitable indicators, given the pH range of the indicatorNo indicator is suitable for a weak acid/weak base titration. The indicator should be considered as a weak acid, HA. 5.1.3(n)(iii) explanation of indicator colour changes in terms of equilibrium shift between the HA and A– forms of the indicatorNo indicator is suitable for a weak acid/weak base titration. The indicator should be considered as a weak acid, HA. 5.1.3(o) the techniques and procedures used when measuring pH with a pH meter.Opportunities to carry out experimental and investigative work. 5.2.1 Lattice enthalpy questions 5.2.1(a) explanation of the term lattice enthalpy (formation of 1 mol of ionic lattice from gaseous ions, ∆LEH) and use as a measure of the strength of ionic bonding in a giant ionic lattice (see also 2.2.2 b– c)Definition required. 5.2.1(b) use of the lattice enthalpy of a simple ionic solid (e.g. NaCl, MgCl2) and relevant energy terms for:Relevant energy terms: enthalpy change of formation, ionisation energy, enthalpy change of atomisation and electron affinity. Definition required for first ionisation energy (see also 3.1.1 c) and enthalpy change of formation (see also 3.2.1 d) only. Application of conservation of energy to determine enthalpy changes. 5.2.1(b)(i) the construction of Born–Haber cyclesRelevant energy terms: enthalpy change of formation, ionisation energy, enthalpy change of atomisation and electron affinity. Definition required for first ionisation energy (see also 3.1.1 c) and enthalpy change of formation (see also 3.2.1 d) only. Application of conservation of energy to determine enthalpy changes. 5.2.1(b)(ii) related calculationsRelevant energy terms: enthalpy change of formation, ionisation energy, enthalpy change of atomisation and electron affinity. Definition required for first ionisation energy (see also 3.1.1 c) and enthalpy change of formation (see also 3.2.1 d) only. Application of conservation of energy to determine enthalpy changes. 5.2.1(c) explanation and use of the terms:Definitions required. Details of infinite dilution not required. 5.2.1(c)(i) enthalpy change of solution (dissolving of 1 mol of solute, ∆solH)Definitions required. Details of infinite dilution not required. 5.2.1(c)(ii) enthalpy change of hydration (dissolving of 1 mol of gaseous ions in water, ∆hydH)Definitions required. Details of infinite dilution not required. 5.2.1(d) use of the enthalpy change of solution of a simple ionic solid (e.g. NaCl, MgCl2) and relevant energy terms (enthalpy change of hydration and lattice enthalpy) for:Application of conservation of energy to determine enthalpy changes. 5.2.1(d)(i) the construction of enthalpy cyclesApplication of conservation of energy to determine enthalpy changes. 5.2.1(d)(ii) related calculationsApplication of conservation of energy to determine enthalpy changes. 5.2.1(e) qualitative explanation of the effect of ionic charge and ionic radius on the exothermic value of a lattice enthalpy and enthalpy change of hydration. 5.2.2 Enthalpy and entropy questions 5.2.2(a) explanation that entropy is a measure of the dispersal of energy in a system which is greater, the more disordered a systemThe model of entropy to explain thermodynamic stability. 5.2.2(b) explanation of the difference in magnitude of the entropy of a system:5.2.2(b)(i) of solids, liquids and gases5.2.2(b)(ii) for a reaction in which there is a change in the number of gaseous molecules5.2.2(c) calculation of the entropy change of a system, ∆S, and related quantities for a reaction given the entropies of the reactants and products5.2.2(d) explanation that the feasibility of a process depends upon the entropy change and temperature in the system, T∆S, and the enthalpy change of the system, ∆H5,6 Use of entropy, enthalpy and temperature for predicting feasibility. 5.2.2(e) explanation, and related calculations, of the free energy change, ∆G, as: ∆ G = ∆H – T∆ S (the Gibbs’ equation) and that a process is feasible when ∆ G has a negative valueLink between ∆G and feasibility. 5.2.2(f) the limitations of predictions made by ∆G about feasibility, in terms of kinetics.The relative effects of entropy and rate in determining feasibility of processes. 5.2.3 Redox and electrode potentials questions 5.3.1 Transition elements questions 5.3.1(a) the electron configuration of atoms and ions of the d-block elements of Period 4 (Sc–Zn), given the atomic number and charge (see also 2.2.1 d)Learners should use sub-shell notation e.g. for Fe: 1s22s22p63s23p63d64s2. 5.3.1(b) the elements Ti–Cu as transition elements i.e. d-block elements that have an ion with an incomplete d-sub-shell5.3.1(c) illustration, using at least two transition elements, of:No detail of how colour arises required. Practical examples of catalytic behaviour include: Cu2+ for reaction of Zn with acids; MnO2for decomposition of H2O2. No detail of catalytic processes required. Benefits of reduced energy usage; risks from toxicity of many transition metals. 5.3.1(c)(i) the existence of more than one oxidation state for each element in its compounds (see also 5.3.1 k)No detail of how colour arises required. Practical examples of catalytic behaviour include: Cu2+ for reaction of Zn with acids; MnO2for decomposition of H2O2. No detail of catalytic processes required. Benefits of reduced energy usage; risks from toxicity of many transition metals. 5.3.1(c)(ii) the formation of coloured ions (see also 5.3.1 h, j– k)No detail of how colour arises required. Practical examples of catalytic behaviour include: Cu2+ for reaction of Zn with acids; MnO2for decomposition of H2O2. No detail of catalytic processes required. Benefits of reduced energy usage; risks from toxicity of many transition metals. 5.3.1(c)(iii) the catalytic behaviour of the elements and their compounds and their importance in the manufacture of chemicals by industry (see 3.2.2 d)No detail of how colour arises required. Practical examples of catalytic behaviour include: Cu2+ for reaction of Zn with acids; MnO2for decomposition of H2O2. No detail of catalytic processes required. Benefits of reduced energy usage; risks from toxicity of many transition metals. 5.3.1(d) explanation and use of the term ligand in terms of coordinate (dative covalent) bonding to a metal ion or metal, including bidentate ligandsExamples should include: monodentate: H2O, Cl– and NH3 bidentate: NH2CH2CH2NH2(‘en’). In exams, other ligands could be introduced. 5.3.1(e) use of the terms complex ion and coordination number and examples of complexes with:Examples: Octahedral: many hexaaqua complexes, e.g. [Cu(H2O)6]2+, [Fe(H2O)6]3+ Tetrahedral: many tetrachloro complexes, e.g. CuCl42– and CoC l42– Square planar: complexes of Pt, e.g. platin: Pt(NH3)2Cl2 (see also 5.3.1 g). 5.3.1(e)(i) six-fold coordination with an octahedral shapeExamples: Octahedral: many hexaaqua complexes, e.g. [Cu(H2O)6]2+, [Fe(H2O)6]3+ Tetrahedral: many tetrachloro complexes, e.g. CuCl42– and CoC l42– Square planar: complexes of Pt, e.g. platin: Pt(NH3)2Cl2 (see also 5.3.1 g). 5.3.1(e)(ii) four-fold coordination with either a planar or tetrahedral shape (see also 2.2.2 g– h)Examples: Octahedral: many hexaaqua complexes, e.g. [Cu(H2O)6]2+, [Fe(H2O)6]3+ Tetrahedral: many tetrachloro complexes, e.g. CuCl42– and CoC l42– Square planar: complexes of Pt, e.g. platin: Pt(NH3)2Cl2 (see also 5.3.1 g). 5.3.1(f) types of stereoisomerism shown by complexes, including those associated with bidentate and multidentate ligands:illustrate stereoisomerism. 5.3.1(f)(i) cis– trans isomerism e.g. Pt(NH3)2Cl2 (see also 4.1.3 c– d)illustrate stereoisomerism. 5.3.1(f)(ii) optical isomerism e.g. [Ni(NH2CH2CH2NH2)3]2+(see also 6.2.2 c)illustrate stereoisomerism. 5.3.1(g) use of cis -platin as an anti-cancer drug and its action by binding to DNA preventing cell divisionBenefits of chemotherapy; risks from unpleasant side effects. 5.3.1(h) ligand substitution reactions and the accompanying colour changes in the formation of:Complexed formulae should be used in ligand substitution equations. 5.3.1(h)(i) [Cu(NH3)4(H2O)2]2+ and [CuC l4]2– from [Cu(H2O)6]2+Complexed formulae should be used in ligand substitution equations. 5.3.1(h)(ii) [Cr(NH3)6]3+ from [Cr(H2O)6]3+ (see also 5.3.1 j)Complexed formulae should be used in ligand substitution equations. 5.3.1(i) explanation of the biochemical importance of iron in haemoglobin, including ligand substitution involving O2and CO5.3.1(j) reactions, including ionic equations, and the accompanying colour changes of aqueous Cu2+, Fe2+, Fe3+, Mn2+ and Cr3+ with aqueous sodium hydroxide and aqueous ammonia, including:For precipitation, non-complexed formulae or complexed formulae, are acceptable e.g. Cu2+(aq) or [Cu(H2O)6]2+; Cu(OH)2(s) or Cu(OH)2(H2O)4. With excess NaOH, only Cr(OH)3reacts further forming [Cr(OH)6]3–. With excess NH3, only Cr(OH)3and Cu(OH)2react forming [Cr(NH3)6]3+ and [Cu(NH3)4(H2O)2]2+ respectively (see also 5.3.1 h). 5.3.1(j)(i) precipitation reactionsFor precipitation, non-complexed formulae or complexed formulae, are acceptable e.g. Cu2+(aq) or [Cu(H2O)6]2+; Cu(OH)2(s) or Cu(OH)2(H2O)4. With excess NaOH, only Cr(OH)3reacts further forming [Cr(OH)6]3–. With excess NH3, only Cr(OH)3and Cu(OH)2react forming [Cr(NH3)6]3+ and [Cu(NH3)4(H2O)2]2+ respectively (see also 5.3.1 h). 5.3.1(j)(ii) complex formation with excess aqueous sodium hydroxide and aqueous ammoniaFor precipitation, non-complexed formulae or complexed formulae, are acceptable e.g. Cu2+(aq) or [Cu(H2O)6]2+; Cu(OH)2(s) or Cu(OH)2(H2O)4. With excess NaOH, only Cr(OH)3reacts further forming [Cr(OH)6]3–. With excess NH3, only Cr(OH)3and Cu(OH)2react forming [Cr(NH3)6]3+ and [Cu(NH3)4(H2O)2]2+ respectively (see also 5.3.1 h). 5.3.1(k) redox reactions and accompanying colour changes for:Fe2+ can be oxidised with H+/MnO4– and Fe3+ reduced with I–, Cr3+ can be oxidised with H2O2/ OH– and Cr2O72– reduced with Zn/H+, Cu2+ can be reduced with I–. In aqueous conditions, Cu+ readily disproportionates. Learners will not be required to recall equations but may be required to construct and interpret redox equations using relevant half-equations and oxidation numbers (see 5.2.3 b– c). 5.3.1(k)(i) interconversions between Fe2+ and Fe3+Fe2+ can be oxidised with H+/MnO4– and Fe3+ reduced with I–, Cr3+ can be oxidised with H2O2/ OH– and Cr2O72– reduced with Zn/H+, Cu2+ can be reduced with I–. In aqueous conditions, Cu+ readily disproportionates. Learners will not be required to recall equations but may be required to construct and interpret redox equations using relevant half-equations and oxidation numbers (see 5.2.3 b– c). 5.3.1(k)(ii) interconversions between Cr3+ and Cr2O72–Fe2+ can be oxidised with H+/MnO4– and Fe3+ reduced with I–, Cr3+ can be oxidised with H2O2/ OH– and Cr2O72– reduced with Zn/H+, Cu2+ can be reduced with I–. In aqueous conditions, Cu+ readily disproportionates. Learners will not be required to recall equations but may be required to construct and interpret redox equations using relevant half-equations and oxidation numbers (see 5.2.3 b– c). 5.3.1(k)(iii) reduction of Cu2+ to Cu+ and disproportionation of Cu+ to Cu2+ and CuFe2+ can be oxidised with H+/MnO4– and Fe3+ reduced with I–, Cr3+ can be oxidised with H2O2/ OH– and Cr2O72– reduced with Zn/H+, Cu2+ can be reduced with I–. In aqueous conditions, Cu+ readily disproportionates. Learners will not be required to recall equations but may be required to construct and interpret redox equations using relevant half-equations and oxidation numbers (see 5.2.3 b– c). 5.3.1(l) interpretation and prediction of unfamiliar reactions including ligand substitution, precipitation, redox. Module 6: Organic chemistry and analysis (A level only; Papers 2 and 3) 6.1.1 Aromatic compounds questions 6.1.1(a) the comparison of the Kekulé model of benzene with the subsequent delocalised models for benzene in terms of p-orbital overlap forming a delocalised π-systemLearners may represent the structure of benzene in equations and mechanisms as: or 7 Development of the model for benzene over time. 6.1.1(b) the experimental evidence for a delocalised, rather than Kekulé, model for benzene in terms of bond lengths, enthalpy change of hydrogenation and resistance to reaction (see also 6.1.1 f)Acceptance of the delocalised benzene model by the scientific community in light of supporting experimental evidence. 6.1.1(c) use of IUPAC rules of nomenclature for systematically naming substituted aromatic compoundsUse of locant numbers to identify positions of substitution e.g. 2,4-dinitromethylbenzene. Introduction of systematic nomenclature. 6.1.1(d) the electrophilic substitution of aromatic compounds with:Halogen carriers include iron, iron halides and aluminium halides. 6.1.1(d)(i) concentrated nitric acid in the presence of concentrated sulfuric acidHalogen carriers include iron, iron halides and aluminium halides. 6.1.1(d)(ii) a halogen in the presence of a halogen carrierHalogen carriers include iron, iron halides and aluminium halides. 6.1.1(d)(iii) a haloalkane or acyl chloride in the presence of a halogen carrier (Friedel–Crafts reaction) and its importance to synthesis by formation of a C–C bond to an aromatic ring (see also 6.2.4 d)Halogen carriers include iron, iron halides and aluminium halides. 6.1.1(e) the mechanism of electrophilic substitution in arenes for nitration and halogenation (see also 4.1.1 h– i)For nitration mechanism, learners should include equations for formation of NO2+. Halogen carriers include iron, iron halides and aluminium halides. For the halogenation mechanism, the electrophile can be assumed to be X+. 2,8 Use of reaction mechanisms to explain organic reactions. 6.1.1(f) the explanation of the relative resistance to bromination of benzene, compared with alkenes, in terms of the delocalised electron density of the π-system in benzene compared with the localised electron density of the π-bond in alkenes (see also 4.1.3 a, 6.1.1 a)5 Use of delocalised benzene model to explain reactivity. 6.1.1(g) the interpretation of unfamiliar electrophilic substitution reactions of aromatic compounds, including prediction of mechanismsExtra information may be provided on exam papers. 6.1.1(h) the weak acidity of phenols shown by the neutralisation reaction with NaOH but absence of reaction with carbonates (see also 5.1.3 b)(see also 6.3.1 c) 6.1.1(i) the electrophilic substitution reactions of phenol:Note that nitration with phenol does not require concentrated HNO3or the presence of a concentrated H2SO4catalyst. 6.1.1(i)(i) with bromine to form 2,4,6-tribromophenolNote that nitration with phenol does not require concentrated HNO3or the presence of a concentrated H2SO4catalyst. 6.1.1(i)(ii) with dilute nitric acid to form a mixture of 2-nitrophenol and 4-nitrophenolNote that nitration with phenol does not require concentrated HNO3or the presence of a concentrated H2SO4catalyst. 6.1.1(j) the relative ease of electrophilic substitution of phenol compared with benzene, in terms of electron pair donation to the π-system from an oxygen p-orbital in phenol (see also 4.1.3 a)Illustrated by reactions with bromine and with nitric acid. Explanation is only in terms of susceptibility of ring to 'attack' and not in terms of stability of intermediate. 5 Use of delocalised benzene model to explain reactivity. 6.1.1(k) the 2- and 4-directing effect of electron- donating groups (OH, NH2) and the 3-directing effect of electron-withdrawing groups (NO2) in electrophilic substitution of aromatic compoundsLearners will not be expected to know further electron-donating or electron-withdrawing groups; relevant additional data will be supplied in examinations. Correlation between substituted group and position of reaction. 6.1.1(l) the prediction of substitution products of aromatic compounds by directing effects and the importance to organic synthesis (see also 6.2.5 Organic Synthesis). 6.1.2 Carbonyl compounds questions 6.1.2(a) oxidation of aldehydes using Cr2O72–/H+ (i.e. K2Cr2O7/H2SO4) to form carboxylic acidsIn equations for organic redox reactions, [O] and [H] should be used. (see also 6.3.1 c) 6.1.2(b) nucleophilic addition reactions of carbonyl compounds with:6.1.2(b)(i) NaBH4to form alcohols6.1.2(b)(ii) HCN [i.e. NaCN(aq)/H+(aq)], to form hydroxynitriles (see also 6.2.4 b)6.1.2(c) the mechanism for nucleophilic addition reactions of aldehydes and ketones with NaBH4 and HCNFor NaBH4, the nucleophile can be considered as being the hydride ion, H–, with subsequent protonation of the organic intermediate from H2O. For HCN, initial nucleophilic attack is from CN– ions; subsequent protonation stage can be shown using H2O or H+. 2,8 Use of reaction mechanisms to explain organic reactions. 6.1.2(d) use of 2,4-dinitrophenylhydrazine to:The equation for this reaction is not required. Structure of derivative not required. (see also 6.3.1 c) Qualitative analysis. 6.1.2(d)(i) detect the presence of a carbonyl group in an organic compoundThe equation for this reaction is not required. Structure of derivative not required. (see also 6.3.1 c) Qualitative analysis. 6.1.2(d)(ii) identify a carbonyl compound from the melting point of the derivativeThe equation for this reaction is not required. Structure of derivative not required. (see also 6.3.1 c) Qualitative analysis. 6.1.2(e) use of Tollens’ reagent (ammoniacal silver nitrate) to:In equations involving Tollens’ reagent, [O] is acceptable. (see also 6.3.1 c) Qualitative analysis. 6.1.2(e)(i) detect the presence of an aldehyde groupIn equations involving Tollens’ reagent, [O] is acceptable. (see also 6.3.1 c) Qualitative analysis. 6.1.2(e)(ii) distinguish between aldehydes and ketones, explained in terms of the oxidation of aldehydes to carboxylic acids with reduction of silver ions to silver.In equations involving Tollens’ reagent, [O] is acceptable. (see also 6.3.1 c) Qualitative analysis. 6.2.2 Amino acids, amides and chirality questions 6.2.4 Carbon– carbon bond formation questions 6.3.1 Chromatography and qualitative analysis questions 6.3.2 Spectroscopy questions 6.3.2(a) analysis of a carbon-13 NMR spectrum of an organic molecule to make predictions about:All carbon-13 NMR spectra that are assessed will be proton decoupled. In examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(a)(i) the number of carbon environments in the moleculeAll carbon-13 NMR spectra that are assessed will be proton decoupled. In examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(a)(ii) the different types of carbon environment present, from chemical shift valuesAll carbon-13 NMR spectra that are assessed will be proton decoupled. In examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(a)(iii) possible structures for the moleculeAll carbon-13 NMR spectra that are assessed will be proton decoupled. In examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(b) analysis of a high resolution proton NMR spectrum of an organic molecule to make predictions about:In examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will be expected to identify aromatic protons from chemical shift values but will not be expected to analyse their splitting patterns. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(b)(i) the number of proton environments in the moleculeIn examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will be expected to identify aromatic protons from chemical shift values but will not be expected to analyse their splitting patterns. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(b)(ii) the different types of proton environment present, from chemical shift valuesIn examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will be expected to identify aromatic protons from chemical shift values but will not be expected to analyse their splitting patterns. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(b)(iii) the relative numbers of each type of proton present from relative peak areas, using integration traces or ratio numbers, when requiredIn examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will be expected to identify aromatic protons from chemical shift values but will not be expected to analyse their splitting patterns. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(b)(iv) the number of non-equivalent protons adjacent to a given proton from the spin– spin splitting pattern, using the n + 1 ruleIn examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will be expected to identify aromatic protons from chemical shift values but will not be expected to analyse their splitting patterns. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(b)(v) possible structures for the moleculeIn examinations, NMR chemical shift values will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will be expected to identify aromatic protons from chemical shift values but will not be expected to analyse their splitting patterns. 5 Interpretation of spectra to analyse organic compounds. 6.3.2(c) prediction of a carbon-13 or proton NMR spectrum for a given molecule6.3.2(d)(i) the use of tetramethylsilane, TMS, as the standard for chemical shift measurements6.3.2(d)(ii) the need for deuterated solvents, e.g. CDCl3, when running an NMR spectrum6.3.2(d)(iii) the identification of O–H and N–H protons by proton exchange using D2O6.3.2(e) deduction of the structures of organic compounds from different analytical data including:Spectral reference data will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Interpretation of a variety of different evidence to analyse organic compounds. 6.3.2(e)(i) elemental analysis (see also 2.1.3 c)Spectral reference data will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Interpretation of a variety of different evidence to analyse organic compounds. 6.3.2(e)(ii) mass spectra (see also 4.2.4 f– g)Spectral reference data will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Interpretation of a variety of different evidence to analyse organic compounds. 6.3.2(e)(iii) IR spectra (see also 4.2.4 d– e)Spectral reference data will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Interpretation of a variety of different evidence to analyse organic compounds. 6.3.2(e)(iv) NMR spectra.Spectral reference data will be provided on the Data Sheet. Restricted to functional groups studied in the A level specification. Learners will not be expected to interpret mass spectra of organic halogen compounds. 5,6 Interpretation of a variety of different evidence to analyse organic compounds. Work with an OCR chemistry tutor Big gaps on the checklist? A tutor can plan the order to close them.
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