B.0 Arithmetic and numerical computation

Recognise and use appropriate units in calculations, including unit conversions. At A2 this includes units for equilibrium and rate constants and conversions between entropy in J mol⁻¹ K⁻¹ and enthalpy changes in kJ mol⁻¹.

Use b.0.0—units in calculations to connect the rule to the data and decision in the question.

This matters because b.0.0—units in calculations determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.0.0—units in calculations to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.0.0—Units in calculations is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Recognise and use decimal, ordinary and standard form; choose appropriate decimal places; calculate with the Avogadro constant; and retain significant figures when converting between forms.

Use b.0.1—decimal and standard form to connect the rule to the data and decision in the question.

This matters because b.0.1—decimal and standard form determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.0.1—decimal and standard form to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.0.1—Decimal and standard form is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Use ratios, fractions and percentages, including percentage yield, atom economy, and constructing or balancing equations from ratios.

Use b.0.2—ratios, fractions and percentages to connect the rule to the data and decision in the question.

This matters because b.0.2—ratios, fractions and percentages determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.0.2—ratios, fractions and percentages to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.0.2—Ratios, fractions and percentages is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Estimate calculation results without a calculator and use estimates to evaluate whether results are reasonable. A2 applications include the effect of changed experimental parameters on measurable values such as Kc.

Use b.0.3—estimating calculation results to connect the rule to the data and decision in the question.

This matters because b.0.3—estimating calculation results determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.0.3—estimating calculation results to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.0.3—Estimating calculation results is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Use calculators to find and use power functions, including calculations with the Avogadro constant. Exponential and logarithmic functions, pH and pKa calculations, and buffer approximations are A2-only applications.

Use b.0.4—powers, exponentials and logarithms to connect the rule to the data and decision in the question.

This matters because b.0.4—powers, exponentials and logarithms determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.0.4—powers, exponentials and logarithms to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.0.4—Powers, exponentials and logarithms is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know and convert between the SI prefixes kilo, centi, milli, micro and nano, as clarified by Pearson for International A Level Chemistry candidates.

Use b.0.p—si unit prefixes to connect the rule to the data and decision in the question.

This matters because b.0.p—si unit prefixes determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.0.p—si unit prefixes to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.0.P—SI unit prefixes is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.