Mathematical Skills - A-Levels Chemistry
Mathematical skills
(i) B.0 – arithmetic and numerical computation
| Mathematical skills | Exemplification of mathematical skill in the context of A Level chemistry (assessment is not limited to the examples given below) | |
|---|---|---|
| B.0.0 | Recognise and make use of appropriate units in calculation | Candidates may be tested on their ability to: • convert between units, e.g. cm3 to dm3 as part of volumetric calculations • give units for an equilibrium constant or a rate constant • understand that different units are used in similar topic areas, so that conversions may be necessary, e.g. entropy in J mol-1 K-1 and enthalpy changes in kJ mol-1 |
| B.0.1 | Recognise and use expressions in decimal and ordinary form | Candidates may be tested on their ability to: • use an appropriate number of decimal places in calculations, e.g. for pH • carry out calculations using numbers in standard and ordinary form, e.g. use of Avogadro's number • understand standard form when applied to areas such as (but not limited to) Kw • convert between numbers in standard and ordinary form • understand that significant figures need retaining when making conversions between standard and ordinary form, e.g. 0.0050 mol dm-3 is equivalent to 5.0 × 10-3 mol dm-3 |
| B.0.2 | Use ratios, fractions and percentages | Candidates may be tested on their ability to: • calculate percentage yields • calculate the atom economy of a reaction • construct and/or balance equations using ratios |
| B.0.3 | Make estimates of the results of calculations (without using a calculator). | Candidates may be tested on their ability to: • evaluate the effect of changing experimental parameters on measurable values, e.g. how the value of Kc would change with temperature given different specified conditions |
| B.0.4 | Use calculators to find and use power, exponential and logarithmic functions | Candidates may be tested on their ability to: • carry out calculations using the Avogadro constant • carry out pH and pKa calculations • make appropriate mathematical approximations in buffer calculations |
(ii) B.1 – handling data
| Mathematical skills | Exemplification of mathematical skill in the context of A Level chemistry (assessment is not limited to the examples given below) | |
|---|---|---|
| B.1.1 | Use an appropriate number of significant figures | Candidates may be tested on their ability to: • report calculations to an appropriate number of significant figures given raw data quoted to varying numbers of significant figures • understand that calculated results can only be reported to the limits of the least accurate measurement |
| B.1.2 | Find arithmetic means | Candidates may be tested on their ability to: • calculate weighted means, e.g. calculation of an atomic mass based on supplied isotopic abundances • select appropriate titration data (i.e. identification of outliers) in order to calculate mean titres |
| B.1.3 | Identify uncertainties in measurements and use simple techniques to determine uncertainty when data are combined | Candidates may be tested on their ability to: • determine uncertainty when two burette readings are used to calculate a titre value |
(iii) B.2 – algebra
| Mathematical skills | Exemplification of mathematical skill in the context of A Level chemistry (assessment is not limited to the examples given below) | |
|---|---|---|
| B.2.1 | Understand and use the symbols: =, <, <<, >>, >, ∝, ~, ⇌ equilibrium sign | No exemplification required. |
| B.2.2 | Change the subject of an equation | Candidates may be tested on their ability to: • carry out structured and unstructured mole calculations, e.g. calculate a rate constant k from a rate equation |
| B.2.3 | Substitute numerical values into algebraic equations using appropriate units for physical quantities | Candidates may be tested on their ability to: • carry out structured and unstructured mole calculations • carry out rate calculations • calculate the value of an equilibrium constant Kc |
| B.2.4 | Solve algebraic equations | Candidates may be tested on their ability to: • carry out Hess's law calculations • calculate a rate constant k from a rate equation |
| B.2.5 | Use logarithms in relation to quantities that range over several orders of magnitude | Students may be tested on their ability to: • carry out pH and pKa calculations |
(iv) B.3 – graphs
| Mathematical skills | Exemplification of mathematical skill in the context of A Level chemistry (assessment is not limited to the examples given below) | |
|---|---|---|
| B.3.1 | Translate information between graphical, numerical and algebraic forms | Candidates may be tested on their ability to: • interpret and analyse spectra • determine the order of a reaction from a graph • derive rate expression from a graph |
| B.3.2 | Plot two variables from experimental or other data | Candidates may be tested on their ability to: • plot concentration–time graphs from collected or supplied data and draw an appropriate best-fit curve |
| B.3.3 | Determine the slope and intercept of a linear graph | Candidates may be tested on their ability to: • calculate the rate constant of a zero-order reaction by determination of the gradient of a concentration–time graph |
| B.3.4 | Calculate rate of change from a graph showing a linear relationship | Candidates may be tested on their ability to: • calculate the rate constant of a zero-order reaction by determination of the gradient of a concentration–time graph |
| B.3.5 | Draw and use the slope of a tangent to a curve as a measure of rate of change | Candidates may be tested on their ability to: • determine the order of a reaction using the initial rates method |
(v) B.4 – geometry and trigonometry
| Mathematical skills | Exemplification of mathematical skill in the context of A Level chemistry (assessment is not limited to the examples given below) | |
|---|---|---|
| B.4.1 | Appreciate angles and shapes in regular 2D and 3D structures. | Candidates may be tested on their ability to: • predict/identify shapes of and bond angles in molecules with and without a lone pair(s), for example NH3, CH4, H2O etc |
| B.4.2 | Visualise and represent 2D and 3D forms including two-dimensional representations of 3D objects | Candidates may be tested on their ability to: • draw different forms of isomers • identify chiral centres from a 2D or 3D representation |
| B.4.3 | Understand the symmetry of 2D and 3D shapes | Candidates may be tested on their ability to: • describe the types of stereoisomerism shown by molecules/complexes • identify chiral centres from a 2D or 3D representation |