Mathematical Skills in Chemistry

What Mathematical Skills in Chemistry covers

Mathematical Skills in Chemistry is examined in all three components: alongside the topics it belongs to on Components 1 and 2, and with extra weight on Component 3, Chemistry in Practice. It covers standard form, units and significant figures, ratios, fractions and percentages, changing the subject and substituting values, logarithms, pH and pKa, Exponentials, the Arrhenius equation and rate, Graphs, gradients and intercepts, Tangents and rates of change, area under a curve, uncertainty and combining errors and the gas equation and equilibrium expressions.

The 10 subtopics

Each one has its own page.

• Standard form, units and significant figuresRecall questions on writing a quantity in standard form, the SI prefixes and converting between them, counting significant figures, the rules for rounding a calculated result, why an answer cannot be more precise than its least precise input, and worked conversions with real chemical quantities.Open →
• Ratios, fractions and percentagesHow a percentage yield is calculated and how the atom economy of a reaction is calculated.Open →
• Changing the subject and substituting valuesRecall questions on rearranging the equations chemistry uses — the mole, concentration, the gas equation, Kc, pH and the Arrhenius equation — to make any symbol the subject, substituting with consistent units, and checking a rearrangement by substituting the answer back.Open →
• Logarithms, pH and pKaRecall questions on what a logarithm is and the relationship between a number and its logarithm, converting between hydrogen ion concentration and pH in both directions, between Ka and pKa, why a change of one pH unit is a factor of ten, and worked conversions.Open →
• Exponentials, the Arrhenius equation and rateRecall questions on the exponential form of the Arrhenius equation and its logarithmic form, what is plotted to obtain a straight line, what the gradient and intercept give, calculating an activation energy from two rate constants, and why a small temperature rise changes the rate so much.Open →
• Graphs, gradients and interceptsRecall questions on choosing which variable goes on each axis, selecting a scale and when a false origin is allowed, drawing a best-fit line, calculating a gradient with its units, what an intercept represents, and reading a chemical quantity off a calibration line.Open →
• Tangents and rates of changeRecall questions on constructing a tangent to a curve and taking its gradient, obtaining an instantaneous rate from a concentration–time graph, why the initial rate is measured at time zero, comparing gradients at different times, and what a levelling curve indicates.Open →
• Area under a curveRecall questions on what the area under a graph represents in a chemical context, estimating it by counting squares or by the trapezium rule, the area under a Boltzmann distribution beyond the activation energy, and interpreting the area under a rate–time graph.Open →
• Uncertainty and combining errorsRecall questions on absolute and percentage uncertainty, the tolerance of common volumetric apparatus, adding absolute uncertainties for a sum or difference and percentage uncertainties for a product or quotient, multiplying by the power for a raised quantity, and quoting a result to match its uncertainty.Open →
• The gas equation and equilibrium expressionsRecall questions on the ideal gas equation and the units each symbol requires, rearranging it for any quantity, worked calculations of volume, pressure and moles, mole fractions and partial pressures, and the algebra of substituting into and rearranging an equilibrium expression.Open →

What you need to know

Answer each one before you reveal it.

Take Mathematical Skills in Chemistry further

The same content, four other ways.

Questions from this topic

Each one with the model answer underneath.

1. 1

   Express a concentration of 0.0050 mol dm⁻³ in standard form, keeping the same number of significant figures.

   Model answer

   It is written 5.0 × 10⁻³ mol dm⁻³, with two significant figures preserved because the trailing zero in 0.0050 is significant.

2. 2

   A titration delivers 22.5 cm³ of solution. Express this volume in dm³.

   Model answer

   There are 1000 cm³ in 1 dm³, so the volume is 22.5 ÷ 1000 = 0.0225 dm³.

3. 3

   Convert a gas volume of 2.50 dm³ into cubic metres.

   Model answer

   One cubic metre contains 1000 dm³, so the volume is 2.50 × 10⁻³ m³.

4. 4

   An enthalpy change is quoted as −45.0 kJ mol⁻¹. Express it in J mol⁻¹ in standard form.

   Model answer

   Multiplying by 1000 gives −45 000 J mol⁻¹, which in standard form is −4.50 × 10⁴ J mol⁻¹.

5. 5

   Why must an entropy change be converted before it is combined with an enthalpy change in the free energy relationship?

   Model answer

   Entropy changes are tabulated in J mol⁻¹ K⁻¹ while enthalpy changes are quoted in kJ mol⁻¹, so one of them must be scaled by a factor of 1000 before they are subtracted, otherwise the answer is out by three orders of magnitude.

6. 6

   How many significant figures does the value 0.02040 mol dm⁻³ contain?

   Model answer

   It contains four, because the zeros before the 2 only fix the decimal point while the zero between the 2 and the 4 and the final zero are both significant.

What is inside Levo

Six ways to work the same material.

Mathematical Skills in Chemistry revision questions

What does Mathematical Skills in Chemistry cover in Eduqas A-Level Chemistry?

10 subtopics: standard form, units and significant figures, ratios, fractions and percentages, changing the subject and substituting values, logarithms, ph and pka, exponentials, the arrhenius equation and rate, graphs, gradients and intercepts, tangents and rates of change, area under a curve, uncertainty and combining errors and the gas equation and equilibrium expressions. Each one has its own page with questions and model answers.

How is Mathematical Skills in Chemistry organised?

By the Eduqas A410QS specification, subtopic by subtopic, so it matches the order you are taught it in.