version 2 – February 2008
QAN 500/2425/5 QAN 500/2347/0
Contents
1 About these Qualifications
1.1 1.2 1.3 1.4 1.5 The Three-Unit AS The Six-Unit Advanced GCE Qualification Titles and Levels Aims Prior Learning/Attainment
4
4 4 5 5 5
2
Summary of Content
2.1 2.2 AS Units A2 Units
6
6 7
3
Unit Content
3.1 3.2 3.3 3.4 3.5 3.6 AS Unit F321: Atoms, Bonds and Groups AS Unit F322: Chains, Energy and Resources AS Unit F323: Practical Skills in Chemistry 1 A2 Unit F324: Rings, Polymers and Analysis A2 Unit F325: Equilibria, Energetics and Elements A2 Unit F326: Practical Skills in Chemistry 2
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8 20 38 40 51 62
4
Schemes of Assessment
4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 AS GCE Scheme of Assessment Advanced GCE Scheme of Assessment Unit Order Unit Options (at AS/A2) Synoptic Assessment (A Level GCE) Assessment Availability Assessment Objectives Quality of Written Communication
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64 65 66 66 66 67 67 68
5
Technical Information
5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Making Unit Entries Making Qualification Entries Grading Result Enquiries and Appeals Shelf-life of Units Unit and Qualification Re-sits Guided Learning Hours Code of Practice/Subject Criteria/Common Criteria Requirements Arrangements for Candidates with Particular Requirements
5.10 Prohibited Qualifications and Classification Code 5.11 Coursework Administration/Regulations
2
6
Other Specification Issues
6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Overlap with other Qualifications Progression from these Qualifications Key Skills Mapping Spiritual, Moral, Ethical, Social, Legislative, Economic and Cultural Issues Sustainable Development, Health and Safety Considerations and European Developments Avoidance of Bias Language Disability Discrimination Act Information Relating to these Specifications
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74 75 75 75 76 76 76 77
Appendix A: Performance Descriptions Appendix B: Chemistry A Data Sheet Appendix C: How Science Works Appendix D: Practical Skills in Chemistry A (Strands and Qualities) Appendix E: Using OCR Interchange to download Practical Skills tasks Appendix F: Mathematical Requirements Appendix G: Health and Safety
78 83 85 90 91 92 93
Vertical black lines indicate a significant change to the previous printed version. Changes can be found on Pages 56 and 85.
This booklet contains OCR’s Advanced Subsidiary (AS) GCE and Advanced GCE specifications in Chemistry A for teaching from September 2008. This specification allows teachers to adopt a flexible approach to the delivery of AS and A Level Chemistry. The course has been designed to enable centres to deliver the designated units (F321– F326) using the framework provided or to design a customised course. This flexible approach is also reflected in the assessment model. All units apart from Unit F323 and Unit F326 are available in both January and June. In both AS and A2, one unit is deliberately shorter, allowing the realistic possibility of using the January assessment series. Thus centres can adopt either a staged or terminal assessment model. There is also a choice of assessed practical tasks available to all centres. The specification is divided into chemical topics, each containing different key concepts of chemistry. Once the key features of a chemical topic have been developed, applications are considered. For assessment purposes, knowledge and understanding of key concepts are treated separately at AS; important links between different areas of chemistry are largely assessed synoptically at A2. While the teaching of practical skills may be integrated with the theoretical topics, they are assessed separately. This allows skills to be developed in a way suited to each individual centre. This specification incorporates the QCA Subject Criteria for Chemistry.
1.1
The Three-Unit AS
The AS GCE is both a ‘stand-alone’ qualification and also the first half of the corresponding Advanced GCE. The AS GCE is assessed at a standard appropriate for candidates who have completed the first year of study (both in terms of teaching time and content) of the corresponding two-year Advanced GCE course, ie between GCSE and Advanced GCE. From September 2008 the AS GCE is made up of three mandatory units, of which two are externally assessed and one is internally assessed. These units form 50% of the corresponding six-unit Advanced GCE.
These qualifications are shown on a certificate as:
OCR Advanced Subsidiary GCE in Chemistry. OCR Advanced GCE in Chemistry.
Both qualifications are Level 3 in the National Qualification Framework (NQF).
1.4
Aims
The aims of these specifications are to encourage candidates to:
develop their interest in, and enthusiasm for chemistry, including developing an interest in further study and careers in chemistry; appreciate how society makes decisions about scientific issues and how the sciences contribute to the success of the economy and society; develop and demonstrate a deeper appreciation of the skills, knowledge and understanding of How Science Works; develop essential knowledge and understanding of different areas of chemistry and how they relate to each other.
1.5
Prior Learning/Attainment
These specifications have been developed for students who wish to continue with a study of chemistry at Level 3 in the National Qualifications Framework (NQF). The AS specification has been written to provide progression from GCSE Science and GCSE Additional Science, or from GCSE Chemistry; achievement at a minimum of grade C in these qualifications should be seen as the normal requisite for entry to AS Chemistry. However, students who have successfully taken other Level 2 qualifications in Science or Applied Science with appropriate chemistry content may also have acquired sufficient knowledge and understanding to begin the AS Chemistry course. Other students without formal qualifications may have acquired sufficient knowledge of chemistry to enable progression onto the course. Recommended prior learning for the AS units is shown in the introduction to each AS unit. The A2 units build upon the knowledge and understanding acquired at AS. Recommended prior learning for the A2 course is successful performance at AS Chemistry.
Atoms and reactions Electrons, bonding and structure The Periodic Table
Unit F322: Chains, Energy and Resources
Basic concepts and hydrocarbons Alcohols, halogenoalkanes and analysis Energy Resources
Unit F323: Practical Skills in Chemistry 1
This AS (practical skills) unit is teacher assessed and externally moderated by OCR. Candidates are assessed on one task from each of the following categories: qualitative, quantitative and evaluative tasks.
Rings, acids and amines Polymers and synthesis Analysis
Unit F325: Equilibria, Energetics and Elements
Rates, equilibrium and pH Energy Transition elements
Unit F326: Practical Skills in Chemistry 2
This A2 (practical skills) unit is teacher assessed and externally moderated by OCR. Candidates are assessed on one task from each of the following categories: qualitative, quantitative and evaluative tasks.
Unit Content
AS Unit F321: Atoms, Bonds and Groups
This unit builds upon the chemical concepts that have been developed at Key Stage 4. The material in F321, Atoms, Bonds and Groups, underpins much of the chemistry encountered in other chemistry units. It is recommended that unit F321 is taught first. This unit consists of three teaching modules:
Module 1: Atoms and Reactions
1.1.1 1.1.2 1.1.3 1.1.4
Atoms Moles and equations Acids Redox
Module 2: Electrons, Bonding and Structure
1.2.1 1.2.2
Electron structure Bonding and structure
Module 3: The Periodic Table
1.3.1 1.3.2 1.3.3
Periodicity Group 2 Group 7
Candidates are expected to apply knowledge, understanding and other skills gained in this unit to new situations and/or to solve related problems. Recommended Prior Knowledge Candidates should:
have achieved Grade C or above in both GCSE Science and GCSE Additional Science, or GCSE Chemistry, or an equivalent standard in other appropriate Level 2 qualifications.
(b) there are patterns in the chemical reactions between substances; (c) new materials are made from natural resources by chemical reactions; (d) the properties of a material determine its uses.
3.7 GCSE Additional Science (ii) Chemistry (a) Structure and Bonding The outer electrons of atoms are involved in chemical reactions. The structure and properties of a substance are strongly dependent on the nature of the bonding that results from the forces between the electrons and nuclei of atoms. (b) Chemical Synthesis Raw materials are converted into new and useful substances by chemical reactions. The theoretical yield of a chemical reaction can be calculated. 1.1 Module 1: Atoms and Reactions This module provides candidates with a knowledge and understanding of atomic structure and the chemical ideas that underpin the study of quantitative chemistry: 1.1.1 Atoms
atomic structure; relative masses.
1.1.2
Moles and Equations
the mole; reacting masses and equations.
1.1.3
Acids
acids and bases; salts.
1.1.4
Redox
oxidation number; redox reactions.
1.1.1 Atoms Context and exemplification Atomic structure
Assessable learning outcomes Candidates should be able to:
(a) describe protons, neutrons and electrons in
The mass of an electron can be assumed to be 1/2000th the mass of a proton.
terms of relative charge and relative mass;
(b) describe the distribution of mass and charge
within an atom; How Science Works 1, 7a:
(c) describe the contribution of protons and
Modern development of the structure of the atom; the changing accepted view of the structure of the atom; acceptance (and
neutrons to the nucleus of an atom, in terms of atomic (proton) number and mass (nucleon) number; 9
rejection) of different theories for the structure (d) deduce the numbers of protons, neutrons and of the atom from the Greeks, Dalton, electrons in: Thompson and Rutherford, Moseley, et al. (i) an atom given its atomic and mass number, (ii) an ion given its atomic number, mass number and ionic charge;
(e) explain the term isotopes as atoms of an
element with different numbers of neutrons and different masses; Relative masses
(f) state that
C is used as the standard measurement of relative masses; relative atomic mass, based on the 12C scale;
12
For simple molecules, the term relative molecular mass will be used.
(g) define the terms relative isotopic mass and
For compounds with giant structures, the term (h) calculate the relative atomic mass of an element given the relative abundances of its relative formula mass will be used. isotopes;
(i) use the terms relative molecular mass and
How Science Works 3:
Use of spreadsheets in calculating relative atomic masses from data; Definitions of relative molecular mass and relative formula mass will not be required.
relative formula mass and calculate values from relative atomic masses.
1.1.2 Moles and Equations Context and exemplification The mole Assessable learning outcomes Candidates should be able to:
(a) explain the terms:
(i)
amount of substance,
(ii) mole (symbol ‘mol’), as the unit for amount of substance, (iii) the Avogadro constant, NA, as the number of particles per mole (6.02 × 1023 mol–1);
(b) define and use the term molar mass (units g
mol–1) as the mass per mole of a substance;
Empirical and molecular formulae
(c) explain the terms:
(i)
empirical formula as the simplest whole number ratio of atoms of each element present in a compound,
(ii) molecular formula as the actual number of atoms of each element in a molecule;
(d) calculate empirical and molecular formulae,
using composition by mass and percentage compositions;
reactions studied and for unfamiliar reactions given reactants and products; Calculation of reacting masses, mole concentrations and volumes of gases
(f) carry out calculations, using amount of
substance in mol, involving: (i) mass, (ii) gas volume, (iii) solution volume and concentration;
(g) deduce stoichiometric relationships from
Candidates will be expected to calculate the above for reactants and products from chemical equations.
calculations;
(h) use the terms concentrated and dilute as
qualitative descriptions for the concentration of a solution. 1.1.3 Acids Context and exemplification Acids and bases Assessable learning outcomes Candidates should be able to:
(a) explain that an acid releases H+ ions in
aqueous solution;
(b) state the formulae of the common acids:
hydrochloric, sulfuric and nitric acids;
(c) state that common bases are metal oxides,
metal hydroxides and ammonia;
(d) state that an alkali is a soluble base that
releases OH– ions in aqueous solution;
(e) state the formulae of the common alkalis:
sodium hydroxide, potassium hydroxide and aqueous ammonia; Salts
(f) explain that a salt is produced when the H+
ion of an acid is replaced by a metal ion or NH4+;
(g) describe the reactions of an acid with
carbonates, bases and alkalis, to form a salt;
(h) explain that a base readily accepts H+ ions
from an acid: eg OH– forming H2O; NH3 forming NH4+; water of crystallisation;
(i) explain the terms anhydrous, hydrated and (j) calculate the formula of a hydrated salt from
given percentage composition, mass composition or experimental data;
(k) perform acid–base titrations, and carry out
1.1.4 Redox Context and exemplification Oxidation number
Assessable learning outcomes Candidates should be able to:
(a) apply rules for assigning oxidation number to
Candidates will not be expected to use oxidation numbers in peroxides or metal hydrides. Ionic equations will only be required in Group 7 chemistry.
atoms in elements, compounds and ions;
(b) describe the terms oxidation and reduction in
terms of: (i) electron transfer, (ii) changes in oxidation number;
(c) use a Roman numeral to indicate the
magnitude of the oxidation state of an element, when a name may be ambiguous, eg nitrate(III) and nitrate(V);
(d) write formulae using oxidation numbers;
Redox reactions
(e) explain that:
(i)
metals generally form ions by losing electrons with an increase in oxidation number to form positive ions,
(ii) non-metals generally react by gaining electrons with a decrease in oxidation number to form negative ions;
For nitric acid, reactions of metals are not expected. Ionic equations not required.
(f) describe the redox reactions of metals with
dilute hydrochloric and dilute sulfuric acids;
(g) interpret and make predictions from redox
equations in terms of oxidation numbers and electron loss/gain.
Practical Skills are assessed using OCR set tasks. The practical work suggested below may be carried out as part of skill development. Centres are not required to carry out all of these experiments:
Making up a standard solution. NaOH or Na2CO3/HCl titration. NaOH/H2SO4 to illustrate difference in stoichiometry. Titration involving a dilution – citric acid in lime juice cordial. Determination of the percentage of water of crystallisation in a hydrated salt. Determination of the relative atomic mass of an unknown metal by gas collection. Determination of the concentration of lime water. Determination of the relative formula mass of washing soda by titration. Reactions of the bases, alkalis and carbonates with acids. Preparation of salts from an acid and a base, eg copper(II) sulfate, ammonium sulphate. Reactions of metals with acids.
In addition to the aims of the scheme, this module provides candidates with a knowledge and understanding of chemical ideas that underpin the study of inorganic chemistry: 1.2.1 Electron Structure
ionisation energies; energy levels, shells, sub-shells, orbitals and electron configuration.
1.2.2
Bonding and Structure
ionic bonding; covalent bonding; the shapes of simple molecules and ions; electronegativity and polarity; intermolecular forces.
1.2.1 Electron Structure Context and exemplification Ionisation energies Assessable learning outcomes Candidates should be able to:
(a) Define the terms first ionisation energy and
successive ionisation energy; Ionisation energy definitions are in terms of (b) Explain that ionisation energies are one mole of gaseous atoms or ions. influenced by nuclear charge, electron shielding and the distance of the outermost How Science Works 1: electron from the nucleus; Evidence for the electron configuration of the atom from successive ionisation energies.
(c) predict from successive ionisation energies of
an element: (i) the number of electrons in each shell of an atom, (ii) the group of the element;
Electrons: electronic energy levels, shells, sub-shells, atomic orbitals, electron configuration
(d) state the number of electrons that can fill the
first four shells;
(e) describe an orbital as a region that can hold
up to two electrons, with opposite spins; For AS, the electron configurations of Cr and (f) describe the shapes of s and p orbitals; Cu, and their ions, will not be tested. (g) state the number of: (i) orbitals making up s-, p- and d-sub Candidates should use sub-shell notation, shells, ie for oxygen: 1s22s22p4. (ii) electrons that occupy s-, p- and d-subshells; How Science Works 1, 7a:
Modern development of the structure of the (h) describe the relative energies of s-, p- and dorbitals for the shells 1, 2, 3 and the 4s and atom (see also 1.1). 4p orbitals;
(ii) ions, given the atomic number and ionic charge, limited to s and p blocks up to Z = 36;
(j) classify the elements into s, p and d blocks.
1.2.2 Bonding and Structure Context and exemplification Ionic bonding Assessable learning outcomes Candidates should be able to:
(a) describe the term ionic bonding as
electrostatic attraction between oppositelycharged ions;
(b) construct ‘dot-and-cross’ diagrams, to
describe ionic bonding;
(c) predict ionic charge from the position of an
element in the Periodic Table;
(d) state the formulae for the following ions: NO3,
CO32–, SO42– and NH4+;
Covalent bonding and dative covalent (coordinate) bonding
(e) describe the term covalent bond as a shared
pair of electrons;
(f) construct ‘dot-and-cross’ diagrams to
describe: (i) single covalent bonding, eg as in H2, Cl2, HCl, H2O, NH3, CH4, BF3 and SF6, (ii) multiple covalent bonding, eg as in O2, N2 and CO2, (iii) dative covalent (coordinate) bonding, eg as in NH4+,
(iv) molecules and ions analogous to those
specified in (i), (ii) and (iii); The shapes of simple molecules and ions
(g) explain that the shape of a simple molecule is
determined by repulsion between electron pairs surrounding a central atom;
(h) state that lone pairs of electrons repel more
(v) H2O (non-linear), (vi) CO2 (linear);
(j) predict the shapes of, and bond angles in,
molecules and ions analogous to those specified in (i); Electronegativity and bond polarity
(k) describe the term electronegativity as the
ability of an atom to attract the bonding electrons in a covalent bond;
(l) explain that a permanent dipole may arise
when covalently-bonded atoms have different electronegativities, resulting in a polar bond; Intermolecular forces
(m) describe intermolecular forces based on
permanent dipoles, as in hydrogen chloride, and induced dipoles (van der Waals’ forces), as in the noble gases;
(n) describe hydrogen bonding, including the role
of a lone pair, between molecules containing –OH and –NH groups, ie as in H2O, NH3 and analogous molecules;
(o) describe and explain the anomalous
properties of H2O resulting from hydrogen bonding, eg: (i) the density of ice compared with water, (ii) its relatively high freezing point and boiling point; Metallic bonding
(p) describe metallic bonding as the attraction of
positive ions to delocalised electrons; No details of cubic or hexagonal packing required.
(q) describe structures as:
Bonding and physical properties
(i)
giant ionic lattices, with strong ionic bonding, ie as in NaCl,
(ii) giant covalent lattices, ie as in diamond and graphite, (iii) giant metallic lattices, (iv) simple molecular lattices, ie as in I2 and ice;
(r) describe, interpret and/or predict physical
(ii) different types of bonding (ionic bonding, covalent bonding, metallic bonding, hydrogen bonding, other intermolecular interactions);
(s) deduce the type of structure and bonding
present from given information. Practical Skills are assessed using OCR set tasks. The practical work suggested below may be carried out as part of skill development. Centres are not required to carry out all of these experiments:
Bonding, structure and physical properties of substances (polarity, electrical conductivity, boiling points, solubility in polar and non-polar solvents).
In addition to the aims of the scheme, this module provides candidates with a knowledge and understanding of chemical ideas that underpin the study of inorganic chemistry: 1.3.1 Periodicity
the Periodic Table; trends in physical properties.
1.3.2
Group 2
redox reactions of Group 2 metals; Group 2 compounds.
1.3.3
Group 7
redox reactions of Group 7 elements; halide tests.
1.3.1 Periodicity Context and exemplification The structure of the Periodic Table in terms of groups and periods How Science Works 1, 7a, 7b:
Assessable learning outcomes Candidates should be able to:
(a) describe the Periodic Table in terms of the
arrangement of elements: (i) by increasing atomic (proton) number, (ii) in periods showing repeating trends in physical and chemical properties, (iii) in groups having similar physical and chemical properties;
(b) describe periodicity in terms of a repeating
Development of the Periodic Table from Döbereiner, Newlands, Mendeleev, Moseley, Seaborg, et al.
pattern across different periods;
(c) explain that atoms of elements in a group
have similar outer shell electron configurations, resulting in similar properties; Periodicity of physical properties of elements (d) describe and explain the variation of the first ionisation energies of elements shown by: (i) a general increase across a period, in Periodic trends in ionisation energies will terms of increasing nuclear charge, consider s and p blocks only. No consideration of the periodic decreases (ii) a decrease down a group in terms of between Groups 2 and 3, and 5 and 6, will be increasing atomic radius and increasing tested. electron shielding outweighing increasing nuclear charge; [See also unit F321: 1.2.1(a)–(c)]
(e) for the elements of Periods 2 and 3:
configurations, atomic radii, melting points and boiling points, (ii) explain variations in melting and boiling points in terms of structure and bonding;
(f) interpret data on electron configurations,
atomic radii, first ionisation energies, melting points and boiling points to demonstrate periodicity. 1.3.2 Group 2 Context and exemplification Redox reactions of Group 2 metals Assessable learning outcomes Candidates should be able to:
(a) describe the redox reactions of the Group 2
elements Mg → Ba: (i) with oxygen, (ii) with water;
(b) explain the trend in reactivity of Group 2
elements down the group due to the increasing ease of forming cations, in terms of atomic size, shielding and nuclear attraction; Reactions of Group 2 compounds
(c) describe the action of water on oxides of
elements in Group 2 and state the approximate pH of any resulting solution;
No explanation of thermal decomposition required.
(d) describe the thermal decomposition of the
carbonates of elements in Group 2 and the trend in their ease of decomposition;
(e) interpret and make predictions from the
chemical and physical properties of Group 2 elements and compounds;
(f) explain the use of Ca(OH)2 in agriculture to
neutralise acid soils; the use of Mg(OH)2 in some indigestion tablets as an antacid. 1.3.3 Group 7 Context and exemplification Characteristic physical properties Assessable learning outcomes Candidates should be able to:
(a) explain, in terms of van der Waals’ forces, the
trend in the boiling points of Cl2, Br2 and I2; Redox reactions and trends in reactivity of Group 7 elements and their compounds
(b) describe the redox reactions, including ionic
elements down the group from the decreasing ease of forming negative ions, in terms of atomic size, shielding and nuclear attraction;
(d) describe the term disproportionation as a
reaction in which an element is simultaneously oxidised and reduced, illustrated by: (i) the reaction of chlorine with water as used in water purification, (ii) the reaction of chlorine with cold, dilute aqueous sodium hydroxide, as used to form bleach, (iii) reactions analogous to those specified in (i) and (ii);
(e) interpret and make predictions from the
How Science Works 6a, 6b:
chemical and physical properties of the Group 7 elements and their compounds;
(f) contrast the benefits of chlorine use in water
Health benefits of chlorine use in water; Ethical implications of adding chlorine to public water supplies (also fluorine in drinking water).
treatment (killing bacteria) with associated risks (hazards of toxic chlorine gas and possible risks from formation of chlorinated hydrocarbons);
(g) describe the precipitation reactions, including
Characteristic reactions of halide ions
Complexes with ammonia are not required.
ionic equations, of the aqueous anions Cl–, Br– and I– with aqueous silver ions, followed by aqueous ammonia; in (g) as a test for different halide ions.
(h) describe the use of the precipitation reactions
Practical Skills are assessed using OCR set tasks. The practical work suggested below may be carried out as part of skill development. Centres are not required to carry out all of these experiments:
Reactions of some Group 2 metals with oxygen and water. Action of water on Group 2 oxides and testing pH of resulting solutions. Thermal decomposition of Group 2 carbonates. Halogen displacement reactions. Testing for the presence of halide ions in solution using silver nitrate.
This unit builds upon the chemical concepts that have been developed at Key Stage 4. This unit consists of four teaching modules: Module 1: Basic Concepts and Hydrocarbons
2.1.1 2.1.2 2.1.3
Basic Concepts Alkanes Alkenes
Module 2: Alcohols, Halogenoalkanes and Analysis
2.2.1 2.2.2 2.2.3
Alcohols Halogenoalkanes Modern Analytical Techniques
Module 3: Energy
2.3.1 2.3.2
Enthalpy Changes Rates and Equilibrium
Module 4: Resources
2.4.1 2.4.2
Chemistry of the Air Green Chemistry
Candidates are expected to apply knowledge, understanding and other skills gained in this unit to new situations and/or to solve related problems. Recommended Prior Knowledge Candidates should:
have achieved Grade C or above in both GCSE Science and GCSE Additional Science, or GCSE Chemistry, or an equivalent standard in other appropriate Level 2 qualifications; have studied Unit F321: Atoms, Bonds and Groups.
Links Science in the National Curriculum This unit expands upon the Key Stage 4: Programme of Study in Science.
3.7 GCSE Science (ii) Chemical and Material Behaviour
(a) chemical change takes place by the rearrangement of atoms in substances; (b) there are patterns in the chemical reactions between substances; (c) new materials are made from natural resources by chemical reactions; (d) the properties of a material determine its uses.
(iv) Environment, Earth and Universe
(a) the effects of human activity on the environment can be assessed using living and non-living
indicators;
(b) the surface and the atmosphere of the Earth have changed since the Earth’s origin and are
changing at present. 3.7 GCSE Additional Science (ii) Chemistry (a) Structure and Bonding The outer electrons of atoms are involved in chemical reactions. The structure and properties of a substance are strongly dependent on the nature of the bonding which results from the forces between the electrons and nuclei of atoms. (b) Chemical Synthesis Raw materials are converted into new and useful substances by chemical reactions. The theoretical yield of a chemical reaction can be calculated.
2.1 Module 1: Basic Concepts and Hydrocarbons This module provides a foundation for the study of organic chemistry and to illustrate and raise issues regarding the applications of organic chemistry to everyday life. This module provides candidates with a knowledge and understanding of chemical ideas that underpin the study of organic chemistry: 2.1.1 Basic Concepts
nomenclature and formula representation; functional groups, organic reactions and isomerism; reaction mechanisms, percentage yield and atom economy.
2.1.2
Alkanes
hydrocarbons from crude oil; hydrocarbons as fuels.
2.1.3
Alkenes
addition reactions; polymers and industrial importance of alkenes.
2.1.1 Basic Concepts Context and exemplification Representing formulae of organic compounds
Assessable learning outcomes Candidates should be able to: (a) interpret and use the terms: (i) empirical formula as the simplest whole number ratio of atoms of each element present in a compound,
See also unit F321: 1.1.2.c,d.
(ii) molecular formula as the actual number of atoms of each element in a molecule, (iii) general formula as the simplest algebraic formula of a member of a homologous series, ie for an alkane: CnH2n + 2,
In structural formulae, the carboxyl group will be represented as COOH and the ester group as COOR. The symbols below will be used for cyclohexane and benzene.
(iv) structural formula as the minimal detail that shows the arrangement of atoms in a molecule, eg for butane: CH3CH2CH2CH3 or CH3(CH2)2CH3, (v) displayed formula as the relative positioning of atoms and the bonds between them, ie for ethanol:
H H C H
H C H O H
(vi) skeletal formula as the simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups, ie for butan-2-ol:
OH
; Functional groups and the naming of organic compounds
(b) interpret, and use, the terms:
(i)
homologous series as a series of organic compounds having the same functional group but with each successive member differing by CH2,
(ii) functional group as a group of atoms responsible for the characteristic reactions of a compound;
(c) use the general formula of a homologous series
to predict the formula of any member of the series;
(d) state the names of the first ten members of the
For AS, nomenclature will be limited to the functional groups studied, ie CH3CH2CH(CH3)CH2OH has the systematic name: 2-methylbutan-1-ol.
(e) use IUPAC rules of nomenclature for
systematically naming organic compounds;
Isomerism
(f) describe and explain the terms:
(i)
Knowledge of E/Z isomerism is restricted to understanding that this system is needed where there are more than two different substituents around the double bond, ie 1,-bromo-2-chloropropene. Candidates are required to identify the E and Z stereoisomers in examples that also have cis and trans isomers such as but-2ene.
structural isomers as compounds with the same molecular formula but different structural formulae,
(ii) stereoisomers as compounds with the same structural formula but with a different arrangement in space, (iii) E/Z isomerism as 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, (iv) cis-trans isomerism as a special case of EIZ isomerism in which two of the substituent groups are the same;
(g) determine the possible structural formulae and/or
H 3C C C
H
H C C
H
H CH3 CH3 H3C E-but-2-ene Z-but-2-ene (trans) (cis) For more complex examples, candidates may be required to identify the feature giving E/Z isomerism, or to draw the E/Z stereoisomers but they will not be required to use Cahn–Ingold–Prelog priority rules to identify which stereoisomer is which.
stereoisomers of an organic molecule, given its molecular formula;
Note that the term geometric isomer is no longer recommended by IUPAC.
(h) describe the different types of covalent bond
Reaction mechanisms
fission: (i) homolytic fission forming two radicals, (ii) heterolytic fission forming a cation and an anion;
Any relevant dipoles should be included. Curly arrows should start from a bond, a lone pair of electrons or a negative charge.
(i) describe a ‘curly arrow’ as the movement of an
electron pair, showing either breaking or formation of a covalent bond;
(j) outline reaction mechanisms, using diagrams, to
show clearly the movement of an electron pair with ‘curly arrows’;
Percentage yields and atom economy
(k) carry out calculations to determine the
percentage yield of a reaction; How Science Works 6a, 7c:
(l) explain the atom economy of a reaction as:
Benefits to society of a high atom economy: see also sustainability: unit F322: 2.4.2.
molecular mass of the desired products 100% ; sum of molecular masses of all products
(m) explain that addition reactions have an atom
economy of a reaction;
(o) describe the benefits of developing chemical
processes with a high atom economy in terms of fewer waste materials;
(p) explain that a reaction may have a high
percentage yield but a low atom economy. 2.1.2 Alkanes
Context and exemplification Hydrocarbons from crude oil Assessable learning outcomes
Candidates should be able to:
(a) explain that a hydrocarbon is a compound of
hydrogen and carbon only;
(b) explain the use of crude oil as a source of
hydrocarbons, separated as fractions with different boiling points by fractional distillation, which can be used as fuels or for processing into petrochemicals;
(c) state that alkanes and cycloalkanes are
saturated hydrocarbons;
(d) state and explain the tetrahedral shape around
each carbon atom in alkanes (see also unit F321: 1.2.2.i);
(e) explain, in terms of van der Waals’ forces, the
variations in the boiling points of alkanes with different carbon-chain length and branching;
Hydrocarbons as fuels
(f) describe the combustion of alkanes, leading to
How Science Works 6b:
their use as fuels in industry, in the home and in transport;
(g) explain, using equations, the incomplete
Toxicity from CO production during incomplete combustion of fuels. Candidates should be aware that a catalyst is required but no detail is expected.
combustion of alkanes in a limited supply of oxygen and outline the potential dangers arising from production of CO in the home and from car use;
(h) describe the use of catalytic cracking to obtain
more useful alkanes and alkenes;
(i) explain that the petroleum industry processes
straight-chain hydrocarbons into branched alkanes and cyclic hydrocarbons to promote efficient combustion; How Science Works 6a, 7b:
(j) contrast the value of fossil fuels for providing
Desirability of renewable fuels by ‘rich’ countries may lead to problems of food supply for countries supplying the ‘crops for fuel’.
energy and raw materials with: (i) the problem of an over-reliance on nonrenewable fossil fuel reserves and the importance of developing renewable plantbased fuels, ie alcohols and biodiesel (see also 2.4.2), (ii) increased CO2 levels from combustion of fossil fuels leading to global warming and climate change (see also 2.4.1.d);
ultraviolet radiation, by Cl2 and by Br2, to form halogenoalkanes;
(l) define the term radical as a species with an
unpaired electron;
Candidates are not required to use ‘half curly arrows’ in this mechanism. Equations should show which species are radicals using a single ‘dot’ to represent the (n) unpaired electron.
(m) describe how homolytic fission leads to the
mechanism of radical substitution in alkanes in terms of initiation, propagation and termination reactions (see also 2.1.1.h); explain the limitations of radical substitution in synthesis, arising from further substitution with formation of a mixture of products.
2.1.3 Alkenes
Context and exemplification Properties of alkenes
Assessable learning outcomes
Candidates should be able to:
(a) state that alkenes and cycloalkenes are
Hybridisation not required.
unsaturated hydrocarbons;
(b) describe the overlap of adjacent p-orbitals to
form a π-bond;
(c) state and explain the trigonal planar shape
around each carbon in the C=C of alkenes (see also unit F321: 1.2.2.i);
Addition reactions of alkenes
(d) describe addition reactions of alkenes, ie by
Candidates are expected to realise that addition to an unsymmetrical alkene such as propene may result in two isomeric products. However, candidates will not be required to predict the relative proportions of these isomers, nor to apply or explain Markovnikoff’s rule.
ethene and propene, with: (i) hydrogen in the presence of a suitable catalyst, ie Ni, to form alkanes, (ii) halogens to form dihalogenoalkanes, including the use of bromine to detect the presence of a double C=C bond as a test for unsaturation, (iii) hydrogen halides to form halogenoalkanes, (iv) steam in the presence of an acid catalyst to form alcohols;
(e) define an electrophile as an electron pair
acceptor;
(f) describe how heterolytic fission leads to the
mechanism of electrophilic addition in alkenes (see also 2.1.1.h–j.);
Polymers from alkenes
(g) describe the addition polymerisation of alkenes; (h) deduce the repeat unit of an addition polymer
obtained from a given monomer;
(i) identify the monomer that would produce a given
section of an addition polymer;
Industrial importance of alkenes
(j) outline the use of alkenes in the industrial
oils using hydrogen and a nickel catalyst, (ii) the formation of a range of polymers using unsaturated monomer units based on the ethene molecule, ie H2C=CHCl, F2C=CF2; How Science Works 6a, 6b, 7c:
(k) outline the processing of waste polymers (see
Benefits from processing of alkenes to produce polymers and plastics; drawbacks from waste polymers. Increased political and social desire to reduce plastic waste, to recycle or to use for energy production. Developments of new degradable plastics produced from renewable resources.
also 2.4.2) by: (i) separation into types (ie PTFE, etc.) and recycling, (ii) combustion for energy production (see 2.1.2.f), (iii) use as a feedstock for cracking (see 2.1.2.h) in the production of plastics and other chemicals;
(l) outline the role of chemists in minimising
environmental damage by: (i) removal of toxic waste products, ie removal of HCl formed during disposal by combustion of halogenated plastics (ie PVC), (ii) development of biodegradable and compostable polymers, ie from isoprene (2methyl-1,3-butadiene), maize and starch (see also 2.4.2).
Practical Skills are assessed using OCR set tasks. The practical work suggested below may be carried out as part of skill development. Centres are not required to carry out all of these experiments.
For simplicity, this module refers to reactions of methane, ethane and propene. It is more convenient to use liquid alkanes and alkenes in practical work. For example, cyclohexane and cyclohexene can be used instead of these gaseous alkanes.
Cracking of paraffin oil. Test-tube reactions of alkanes and alkenes with bromine. Extraction of limonene from orange peel.
2.2 Module 2: Alcohols, Halogenoalkanes and Analysis This module extends the knowledge base in organic chemistry by study of two further functional groups: 2.2.1 Alcohols
properties of alcohols and the preparation of ethanol; reactions, including oxidation, esterification and elimination.
2.2.2
Halogenoalkanes
substitution reactions and uses.
2.2.3
Modern Analytical Techniques
infrared spectroscopy; mass spectrometry.
This analytical work is developed further in Advanced GCE Chemistry.
Links
AS Unit F321: Atoms, Bonds and Groups
1.2.2 Bonding and Structure (intermolecular forces)
AS Unit F322: Chains, Energy and Resources
2.1.1 Basic Concepts 2.1.2 Alkanes 2.1.3 Alkenes 2.4.1 Chemistry of the Air
2.2.1 Alcohols
Context and exemplification Properties and preparation of ethanol Assessable learning outcomes
Candidates should be able to:
(a) explain, in terms of hydrogen bonding, the
water solubility and the relatively low volatility of alcohols;
(b) describe the industrial production of ethanol
by: (i)
fermentation from sugars, ie from glucose,
H3PO4 is usually used as the acid catalyst.
(ii) the reaction of ethene with steam in the presence of an acid catalyst;
(c) outline, for alcohols:
(i)
the use of ethanol in alcoholic drinks and as a solvent in the form of methylated spirits,
27
(ii) the use of methanol as a petrol additive to improve combustion and its increasing importance as a feedstock in the production of organic chemicals;
Reactions of alcohols
(d) classify alcohols into primary, secondary and
tertiary alcohols;
(e) describe the combustion of alcohols;
Equations should use [O] to represent the oxidising agent.
(f) describe the oxidation of alcohols using
Cr2O72–/H+ (ie K2Cr2O7/H2SO4), including: (i) the oxidation of primary alcohols to form aldehydes and carboxylic acids; the control of the oxidation product using different reaction conditions, (ii) the oxidation of secondary alcohols to form ketones, (iii) the resistance to oxidation of tertiary alcohols;
(g) describe the esterification of alcohols with
carboxylic acids in the presence of an acid catalyst;
Mechanism for elimination not required. H3PO4 or H2SO4 is usually used as the acid catalyst.
(h) describe elimination of H2O from alcohols in
the presence of an acid catalyst and heat to form alkenes.
2.2.2 Halogenoalkanes
Context and exemplification Substitution reactions of halogenoalkanes Assessable learning outcomes
Candidates should be able to:
(a) describe the hydrolysis of halogenoalkanes
as a substitution reaction;
(b) define the term nucleophile as an electron
pair donor;
(c) describe the mechanism of nucleophilic
substitution in the hydrolysis of primary halogenoalkanes with hot aqueous alkali (see also 2.1.1.i,j); Aqueous silver nitrate in ethanol can be used (d) explain the rates of hydrolysis of primary halogenoalkanes in terms of the relative bond to compare these rates. In this reaction, H2O enthalpies of carbon–halogen bonds (C–F, can be assumed to be the nucleophile. C–Cl, C–Br and C–I); Alternatively, hot aqueous alkali can be used (followed by neutralisation and addition of aqueous silver nitrate). In this reaction, OH– is the nucleophile.
Uses of halogenoalkanes
(e) outline the uses of chloroethene and
How Science Works 6a, 6b, 7a–c:
tetrafluoroethene to produce the plastics PVC and PTFE (see also 2.1.3.g–i);
This provided important evidence which enabled international action to be taken to reduce and phase out CFC use.
because of their low reactivity, volatility and non-toxicity,
(ii) have caused environmental damage to This has subsequently led to development of the ozone layer (see also 2.4.1.g); ozone-friendly alternatives and natural repair (g) outline the role of green chemistry in of the ozone layer. minimising damage to the environment by promoting biodegradable alternatives to CFCs, such as hydrocarbons and HCFCs; CO2 as a blowing agent for expanded polymers (see also 2.4.2).
2.2.3 Modern Analytical Techniques
Context and exemplification Infrared spectroscopy
Assessable learning outcomes
Candidates should be able to:
(a) state that absorption of infrared radiation
causes covalent bonds to vibrate; In examinations, infrared absorption data will be provided on the Data Sheet. (b) identify, using an infrared spectrum of an organic compound: Candidates should be aware that most (i) an alcohol from an absorption peak of organic compounds produce a peak at –1 the O–H bond, approximately 3000 cm due to absorption by C–H bonds. (ii) an aldehyde or ketone from an absorption peak of the C=O bond, (iii) a carboxylic acid from an absorption peak of the C=O bond and a broad absorption peak of the OH bond;
How Science Works 7c:
Use of analytical techniques to inform decision (c) state that modern breathalysers measure making, ie breathalysers in drink driving ethanol in the breath by analysis using cases. infrared spectroscopy;
(d) outline the use of mass spectrometry:
Mass spectrometry
(i) How Science Works 3:
in the determination of relative isotopic masses,
Is there life on Mars?, how much lead/pesticides enters the food chain via vegetables, etc. Knowledge of the mass spectrometer is not required. Limited to ions with single charges. Rearrangement reactions are not required.
(ii) as a method for identifying elements, ie use in the Mars space probe and in monitoring levels of environmental pollution, such as lead;
(e) interpret mass spectra of elements in terms
of isotopic abundances;
(f) use the molecular ion peak in a mass
spectrum of an organic molecule to Mass spectra limited to alkanes, alkenes and determine its molecular mass; alcohols. (g) suggest the identity of the major fragment ions, ie m/z = 29 as CH3CH2+, in a given mass spectrum (limited to alkanes, alkenes and alcohols);
(h) use molecular ion peaks and fragmentation
unipositive ions);
(i) explain that a mass spectrum is essentially a
fingerprint for the molecule that can be identified by computer using a spectral database.
Practical Skills are assessed using OCR set tasks. The practical work suggested below may be carried out as part of skill development. Centres are not required to carry out all of these experiments:
Fermentation of glucose. Oxidation of ethanol to aldehyde and carboxylic acid. Elimination of water from cyclohexanol. Preparation of esters on a test-tube scale. Rates of hydrolysis of different halogenoalkanes. Interpretation of spectra – spectra available at: http://riodb01.ibase.aist.go.jp/sdbs/cgibin/cre_index.cgi?lang=eng
2.3 Module 3: Energy This module provides candidates with a knowledge and understanding of chemical reasoning that underpins the study of physical chemistry. 2.3.1 Enthalpy Changes
enthalpy changes of reaction, combustion and formation; bond enthalpies; Hess’ law and enthalpy cycles.
2.3.2
Rates and Equilibrium
collision theory, the Boltzmann distribution and catalysis; a qualitative study of reaction rates; dynamic equilibrium and le Chatelier’s principle.
Links AS Unit F321: Atoms, Bonds and Groups
1.1.2 Moles and Equations 1.3.2 Group 2 (acid reactions with metals, carbonates and bases) 2.1.2 Alkanes (combustion of fuels) 2.2.1 Alcohols (combustion of alcohols)
AS Unit F322: Chains, Energy and Resources
2.3.1 Enthalpy Changes
Context and exemplification Assessable learning outcomes
Enthalpy changes: ∆H of reaction, formation Candidates should be able to: and combustion (a) explain that some chemical reactions are accompanied by enthalpy changes that can be exothermic (∆H, negative) or endothermic (∆H, positive);
(b) describe the importance of oxidation as an
exothermic process in the combustion of fuels and the oxidation of carbohydrates such as glucose in respiration;
(c) describe that endothermic processes require
an input of heat energy, eg the thermal decomposition of calcium carbonate;
(d) construct a simple enthalpy profile diagram
for a reaction to show the difference in the enthalpy of the reactants compared with that of the products;
(e) explain qualitatively, using enthalpy profile
Standard conditions can be considered as 100 kPa and a stated temperature, 298 K.
(f) define and use the terms:
(i)
standard conditions,
(ii) enthalpy change of reaction, (iii) enthalpy change of formation, (iv) enthalpy change of combustion;
(g) calculate enthalpy changes from appropriate
experimental results directly, including use of the relationship: energy change = mc∆T;
Bond enthalpies
(h) explain exothermic and endothermic
reactions in terms of enthalpy changes associated with the breaking and making of chemical bonds;
(i) define and use the term average bond
enthalpy (∆H positive; bond breaking of one mole of bonds);
(j) calculate an enthalpy change of reaction from
average bond enthalpies;
Hess’ law and enthalpy cycles
(k) use Hess’ law to construct enthalpy cycles
and carry out calculations to determine: (i) an enthalpy change of reaction from enthalpy changes of combustion,
Unfamiliar enthalpy cycles will be provided.
(ii) an enthalpy change of reaction from enthalpy changes of formation, (iii) an enthalpy change of reaction from an unfamiliar enthalpy cycle. 2.3.2 Rates and Equilibrium
Context and exemplification Simple collision theory Assessable learning outcomes
Candidates should be able to: (a) describe qualitatively, in terms of collision theory, the effect of concentration changes on the rate of a reaction;
(b) explain why an increase in the pressure of a
gas, increasing its concentration, may increase the rate of a reaction involving gases;
Catalysts
(c) state that a catalyst speeds up a reaction
(ii) enable different reactions to be used, with better atom economy and with reduced waste, (iii) are often enzymes, generating very specific products, and operating effectively close to room temperatures and pressures, (iv) have great economic importance, eg iron in ammonia production, Ziegler– Natta catalyst in poly(ethene) production, platinum/palladium/rhodium in catalytic converters (see also 2.4.1.i);
(e) explain, using enthalpy profile diagrams, how
the presence of a catalyst allows a reaction to proceed via a different route with a lower activation energy, giving rise to an increased reaction rate;
The Boltzmann distribution
(f) explain qualitatively the Boltzmann
How Science Works 1:
distribution and its relationship with activation energy;
(g) describe qualitatively, using the Boltzmann
The Boltzmann distribution as a theoretical model arising from kinetic theory.
distribution, the effect of temperature changes on the proportion of molecules exceeding the activation energy and hence the reaction rate;
(h) interpret the catalytic behaviour in (e), in
terms of the Boltzmann distribution;
Dynamic equilibrium and le Chatelier’s principle
(i) explain that a dynamic equilibrium exists
when the rate of the forward reaction is equal to the rate of the reverse reaction;
(j) state le Chatelier’s principle; (k) apply le Chatelier’s principle to deduce
qualitatively (from appropriate information) the effect of a change in temperature, concentration or pressure, on a homogeneous system in equilibrium;
(l) explain, from given data, the importance in
the chemical industry of a compromise between chemical equilibrium and reaction rate.
Practical Skills are assessed using OCR set tasks. The practical work suggested below may be carried out as part of skill development. Centres are not required to carry out all of these experiments.
Direct enthalpy changes of reaction for simple reactions: Zn + CuSO4 (exo); NaHCO3 + citric acid (endo); NaOH + HCl (exo). Enthalpy change of combustion of alcohols. Indirect enthalpy change of reaction: 2KHCO3 → K2CO3 + H2O + CO2 indirectly using HCl. Rate graphs for gas products, eg CaCO3 + HCl; Mg + HCl Changing equilibrium position with heat: [Cu(H2O)6]2+ ⇌ CuCl42– Changing equilibrium position with concentration: Fe3+ and SCN–
2.4 Module 4: Resources The emphasis here is on the application of chemical facts and principles to processes occurring in the environment and to the difficulties in providing solutions to pollution. It is important that candidates should appreciate this aspect, bearing in mind the increasing concern, both national and international, for protecting the environment and promoting ‘Green Chemistry’. 2.4.1 Chemistry of the Air
the ‘Greenhouse Effect’; the ozone layer; controlling pollution.
2.4.2
Green Chemistry
sustainability.
Links
AS Unit F322: Chains, Energy and Resources
2.1.2 Alkanes (radicals; combustion of fuels) 2.2.2 Halogenoalkanes (CFCs) 2.2.3 Modern Analytical Techniques 2.3.2 Rates and Equilibrium (reversible reactions; catalysts)
2.4.1 Chemistry of the Air
Context and exemplification The ‘Greenhouse Effect’ Assessable learning outcomes
Candidates should be able to:
(a) explain that infrared radiation is absorbed by
How Science Works 7a, 7c:
Collecting data to confirm whether or not climate change is occurring; monitoring measures to abate the change; modelling the (b) explain that the ‘Greenhouse Effect’ of a given gas is dependent both on its potential damage. atmospheric concentration and its ability to absorb infrared radiation;
(c) outline the importance of controlling global
C=O, O–H and C–H bonds in H2O, CO2 and CH4, and that these absorptions contribute to global warming;
warming resulting from atmospheric increases in greenhouse gases;
(d) outline the role of chemists in minimising
storage, CCS, ie the removal of waste carbon dioxide as a liquid injected deep in the oceans, storage in deep geological formations, by reaction with metal oxides to form stable carbonate minerals,
(iii) monitoring progress against initiatives such as the Kyoto protocol;
The ozone layer
(e) explain that ozone is continuously being
formed and broken down in the stratosphere by the action of ultraviolet radiation;
(f) using the chemical equilibrium, below:
(i)
O2 + O ⇌ O3 describe and explain how the concentration of ozone is maintained in the ozone layer, including the role of ultraviolet radiation,
(ii) outline the role of ozone in the absorption of harmful ultraviolet radiation and the essential benefit of this process for life on Earth; How Science Works 6a, 6b: Benefits of use of CFCs and consequent breakdown of ozone layer.
(g) understand that radicals, eg from CFCs, and
No specific equations will be required beyond this simple representation of this catalysis.
NOx from thunderstorms or aircraft, may catalyse the breakdown of ozone by the following simple representation: R + O3 RO + O2 RO + O R + O2 where R represents Cl• from a CFC or NO from nitrogen oxides;
(h) for carbon monoxide, oxides of nitrogen and
Controlling air pollution
No details are required of the chemical processes involved in formation of photochemical smog.
unburnt hydrocarbons: (i) explain their formation from the internal combustion engine, (ii) state environmental concerns from their toxicity and contribution to low-level ozone and photochemical smog;
(i) outline how a catalytic converter decreases
Candidates should understand that bonding to the catalyst surface must be weak enough for adsorption and desorption to take place but strong enough to weaken bonds and allow reaction to take place.
carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: (i) adsorption of CO and NO to the catalyst surface, (ii) chemical reaction, (iii) desorption of CO2 and N2 from the catalyst surface;
(j) outline the use of infrared spectroscopy in
2.4.2 Green Chemistry How Science Works 6a, 6b, 7c:
The use of context case studies such as those below to demonstrate current principles of chemical sustainability; desirability of such processes economically and environmentally; appreciation that legislation may be required to enforce environmentally desirable processes; the inbuilt desirability from within the chemical community to clean up their act.
Assessable learning outcomes
Context and exemplification Sustainability
Candidates should be able to:
(a) describe principles of chemical sustainability:
Examples for (a) (not examinable):
Lead has largely been eliminated from use in petrol, paints and electrical components. New foams such as Pyrocool® FEF have been invented to put out fires effectively without producing the toxic or ozone-depleting waste products found in other halogenated fire-fighting materials. Solvent-free reactions, ie use of reagent as solvent. For dry cleaning, liquid ‘supercritical’ CO2 can be used as a safer solvent than chlorinated hydrocarbons. Fossil fuels are being replaced or supplemented by renewable fuels, such as biodiesel, alcohol and fuel cells. Increased use of recycling of manufactured materials such as plastics, glass and metals.
(i)
using industrial processes that reduce or eliminate hazardous chemicals and which involve the use of fewer chemicals,
(ii) designing processes with a high atom economy that minimise the production of waste materials, (iii) using renewable resources such as plant-based substances, (iv) seeking alternative energy sources such as solar energy, rather than consuming finite resources such as fossil fuels that will eventually be exhausted, (v) ensuring that any waste products produced are non-toxic, and can be recycled or biodegraded by being broken down into harmless substances in the environment;
Examples for (b) (not examinable):
Production of biodiesel uses grain crops and land needed for food, with poorer countries (b) explain that the apparent benefits may be being worse affected. offset by unexpected and detrimental sideeffects; Examples for (c) (not examinable):
Montreal Protocol on Substances that Deplete (c) explain the importance of establishing international cooperation to promote the the Ozone Layer. reduction of pollution levels; Global Treaty on Persistent Organic (d) discuss issues of sustainability in contexts Pollutants. based on the principles in a–c; Rio Declaration on Environment and Development.
This unit assesses practical and investigative skills developed within contexts encountered during AS Chemistry. Further information on the assessment of the tasks is provided as Appendix D. Candidates are required to carry out three tasks: 1. 2. 3. Qualitative task Quantitative task Evaluative task [10 marks] [15 marks] [15 marks]
Tasks will be chosen from a selection provided by OCR. The Qualitative and Quantitative tasks will test skills of observation and measurement. Candidates will carry out these tasks under controlled conditions. Each task will be internally assessed using a mark scheme provided by OCR. Candidates may attempt more than one task from each category with the best mark from each category being used to make up the overall mark. Centres will supply OCR with a single mark out of 40.
How Science Works 5a Carry out experimental and investigative activities, including appropriate risk management, in a range of contexts. 5b Analyse and interpret data to provide evidence, recognising correlations and causal relationships. 5c Evaluate methodology, evidence and data, and resolve conflicting evidence.
The mark schemes supplied by OCR will be based on the following generic criteria:
Candidates should be able to:
(a) demonstrate skilful and safe practical
Candidates carry out a practical task using instructions supplied by OCR.
techniques using suitable qualitative methods;
(b) make and record valid observations,
organise results suitably.
2.
Quantitative Task
Candidates should be able to:
(a) demonstrate skilful and safe practical
Candidates carry out a practical task using instructions supplied by OCR.
techniques using suitable quantitative methods;
(b) make and record accurate measurements to
an appropriate precision;
(c) analyse, interpret and evaluate
experimentally derived results quantitatively to reach valid conclusions.
3.
Evaluative Task
Candidates should be able to:
(a) analyse and interpret data, identify anomalies
and reach valid conclusions; This task may extend one of the qualitative or quantitative tasks. (b) assess the reliability and accuracy of an experimental task, Candidates will evaluate the quality of the identify significant weaknesses in data and procedures. experimental procedures and measurements; Evaluative tasks will not require additional (c) understand and select simple improvements data collection. to experimental procedures and measurements.
The Tasks
Tasks, mark schemes and guidance for teachers and technicians can be downloaded from the OCR Interchange site. Further advice and guidance on the use and marking of the tasks can be found in the Practical Skills Handbook.
This unit builds upon the chemical concepts that have been developed during AS Chemistry. This unit consists of three teaching modules:
Module 1: Rings, Acids and Amines
4.1.1 4.1.2 4.1.3 4.1.4
Arenes Carbonyl Compounds Carboxylic Acids and Esters Amines
Module 2: Polymers and Synthesis
4.2.1 4.2.2 4.2.3
Amino Acids and Proteins Polyesters and Polyamides Synthesis
Module 3: Analysis
4.3.1 4.3.2
Chromatography Spectroscopy
Candidates are expected to apply knowledge, understanding and other skills gained in this unit to new situations and/or to solve related problems.
Recommended Prior Knowledge
Candidates should:
have studied AS Chemistry.
4.1 Module 1: Rings, Acids and Amines This module provides candidates with a deeper knowledge and understanding of how organic chemistry shapes the natural world and how organic chemicals provide many important materials. This module provides candidates with a knowledge and understanding of organic chemistry: 4.1.1 Arenes
structure of benzene, electrophilic substitution; phenols.
properties; esters, triglycerides, unsaturated and saturated fats.
4.1.4
Amines
basicity and preparation; azo dyes.
The material covered in this module builds on, and develops, the knowledge and understanding of functional groups encountered in AS Chemistry. Unit F322 should be consulted for important information about formulae (2.1.1) and reaction mechanisms (2.1.1.h–j).
Links
AS Unit F321: Atoms, Bonds and Groups
1.1.2 Moles and Equations 1.2.2 Bonding and Structure
AS Unit F322: Chains, Energy and Resources
2.1.1 Basic Concepts 2.1.2 Alkanes 2.1.3 Alkenes 2.2.1 Alcohols 2.2.2 Halogenoalkanes 2.4.1 Chemistry of the Air
4.1.1 Arenes
Context and exemplification Structure of benzene Assessable learning outcomes
Candidates should be able to:
(a) compare the Kekulé and delocalised models for
How Science Works 1, 7a:
The development and acceptance of models for the structure of benzene. Students may represent the structure of benzene as or and mechanisms. in equations
benzene in terms of p-orbital overlap forming π bonds;
(b) review the evidence for a delocalised model of
benzene in terms of bond lengths, enthalpy change of hydrogenation and resistance to reaction [see also (e) below];
Electrophilic substitution of arenes
(c) describe the electrophilic substitution of arenes
Halogen carriers include iron, iron halides and aluminium halides.
with (i) concentrated nitric acid in the presence of concentrated sulfuric acid,
For nitration, candidates should include equations for formation of NO2+ For halogenation, candidates should include equations for formation of X+ or δ+X–AlX3δ–.
(ii) a halogen in the presence of a halogen carrier;
(d) outline the mechanism of electrophilic
substitution in arenes, using the mononitration and monohalogenation of benzene as examples (see also unit F322: 2.1.1.h–j);
(e) explain the relative resistance to bromination of
benzene, compared with alkenes, in terms of the delocalised electron density of the π bonds in benzene compared with the localised electron density of the C=C bond in alkenes;
Phenols
(f) describe the reactions of phenol:
(i)
with aqueous alkalis and with sodium to form salts,
(ii) with bromine to form 2,4,6-tribromophenol;
(g) explain the relative ease of bromination of phenol
compared with benzene, in terms of electron-pair donation to the benzene ring from an oxygen porbital in phenol;
(h) state the uses of phenols in production of
plastics, antiseptics, disinfectants and resins for paints. 4.1.2 Carbonyl Compounds
Context and exemplification Reactions of carbonyl compounds
Assessable learning outcomes
Candidates should be able to: (a) describe the oxidation of alcohols (see also unit F322: 2.2.1.f) using Cr2O72–/H+ (ie K2Cr2O7/H2SO4), including: (i) the oxidation of primary alcohols to form aldehydes and carboxylic acids; the control of the oxidation product using different reaction conditions, (ii) the oxidation of secondary alcohols to form ketones; (b) describe the oxidation of aldehydes using Cr2O72–/H+ to form carboxylic acids;
In equations for organic redox reactions, [O] and [H] should be used.
(c) The nucleophile can be considered as – being the hydride ion, H , with subsequent protonation of the organic intermediate (d) from H2O.
(e) describe the use of 2,4-dinitrophenylhydrazine
42
The equation for this reaction is not required. Structure of derivative not required.
an organic compound, (ii) identify a carbonyl compound from the melting point of the derivative;
(f) describe the use of Tollens’ reagent (ammoniacal
In equations involving Tollens’ reagent, [O] is acceptable.
silver nitrate) to: (i) detect the presence of an aldehyde group, (ii) distinguish between aldehydes and ketones, explained in terms of the oxidation of aldehydes to carboxylic acids with reduction of silver ions to silver.
4.1.3 Carboxylic Acids and Esters
Context and exemplification Properties of carboxylic acids
Assessable learning outcomes
Candidates should be able to:
(a) explain the water solubility of carboxylic acids in
Comparison of acidity of different carboxylic acids not required.
terms of hydrogen bonding and dipole–dipole interaction;
(b) describe the reactions of carboxylic acids with
metals, carbonates and bases;
Esters, triglycerides, unsaturated and saturated fats
(c) describe esterification of carboxylic acids with
alcohols, in the presence of an acid catalyst (see also 2.2.1.g); of acid anhydrides with alcohols;
(d) describe the hydrolysis of esters:
(i)
in hot aqueous acid to form carboxylic acids and alcohols,
(ii) in hot aqueous alkali to form carboxylate salts and alcohols;
(e) state the uses of esters in perfumes and
flavourings; How Science Works 6b:
(f) describe a triglyceride as a triester of glycerol
(propane-1,2,3-triol) and fatty acids;
(g) compare the structures of saturated fats,
Examples: octadecanoic acid,18,0; octadec-9-enoic acid, 18,1(9); octadec-9,12-enoic acid, 18,2(9,12) Link between unsaturated and saturated fats and current concerns about heart disease and obesity.
unsaturated fats and fatty acids, including cis and trans isomers, from systematic names and shorthand formulae;
(h) compare the link between trans fatty acids, the
possible increase in ‘bad’ cholesterol and the resultant increased risk of coronary heart disease and strokes;
(i) describe and explain the increased use of esters
How Science Works 7c:
Use of biodiesel as a fuel to increase contribution to energy requirements from renewable fuels.
4.1.4 Amines
Context and exemplification Basicity of amines
Assessable learning outcomes
Candidates should be able to:
(a) explain the basicity of amines in terms of proton
acceptance by the nitrogen lone pair; Comparison of basicity of different amines not required. (b) describe the reactions of amines with acids to form salts;
(c) describe the preparation of:
Preparation of amines
(i)
aliphatic amines by substitution of halogenoalkanes with excess ethanolic ammonia,
(ii) aromatic amines by reduction of nitroarenes using tin and concentrated hydrochloric acid;
Synthesis of azo dyes
(d) describe the synthesis of an azo dye by reaction
