Topic 1: Formulae, Equations and Amount of Substance

Know the terms ‘atom', 'element', 'ion', 'molecule', 'compound', 'empirical formula' and 'molecular formula’.

Use —the terms ‘atom', 'element', 'ion', 'molecule', 'compound', 'empirical formula' and 'molecular formula’ to connect the rule to the data and decision in the question.

This matters because —the terms ‘atom', 'element', 'ion', 'molecule', 'compound', 'empirical formula' and 'molecular formula’ determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the terms ‘atom', 'element', 'ion', 'molecule', 'compound', 'empirical formula' and 'molecular formula’ to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Know that the mole (mol) is the unit for the amount of a substance and be able to perform calculations using the Avogadro constant L (6.02 × 10²³ mol⁻¹).

Use —the mole (mol) is the unit for the amount of a substance to connect the rule to the data and decision in the question.

This matters because —the mole (mol) is the unit for the amount of a substance determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the mole (mol) is the unit for the amount of a substance to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The mole (mol) is the unit for the amount of a substance is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Write balanced full and ionic equations, including state symbols, for chemical reactions.

Use —write balanced full and ionic equations to connect the rule to the data and decision in the question.

This matters because —write balanced full and ionic equations determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —write balanced full and ionic equations to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Understand the terms: i ‘relative atomic mass’ based on the 12C scale ii ‘relative molecular mass’ and ‘relative formula mass’, including calculating these values from relative atomic masses The term ‘relative formula mass’ should be used for compounds with giant structures. iii ‘molar mass’ as the mass per mole of a substance in g mol⁻¹ iv parts per million (ppm), including gases in the atmosphere.

Use —the terms: i ‘relative atomic mass’ based on the 12c scale ii ‘relative molecular mass’ and ‘relative formula mass’ to connect the rule to the data and decision in the question.

This matters because —the terms: i ‘relative atomic mass’ based on the 12c scale ii ‘relative molecular mass’ and ‘relative formula mass’ determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the terms: i ‘relative atomic mass’ based on the 12c scale ii ‘relative molecular mass’ and ‘relative formula mass’ to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Calculate the concentration of a solution in mol dm−3 and g dm−3 Titration calculations are not required at this stage.

Use —the concentration of a solution in mol dm−3 and g dm−3 titration calculations are not required at this stage to connect the rule to the data and decision in the question.

This matters because —the concentration of a solution in mol dm−3 and g dm−3 titration calculations are not required at this stage determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the concentration of a solution in mol dm−3 and g dm−3 titration calculations are not required at this stage to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The concentration of a solution in mol dm−3 and g dm−3 Titration calculations are not required at this stage is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to use experimental data to calculate empirical and molecular formulae.

Use —experimental data to calculate empirical and molecular formulae to connect the rule to the data and decision in the question.

This matters because —experimental data to calculate empirical and molecular formulae determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —experimental data to calculate empirical and molecular formulae to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Be able to use chemical equations to calculate reacting masses and vice versa, using the concepts of amount of substance and molar mass.

Use —chemical equations to calculate reacting masses and vice versa to connect the rule to the data and decision in the question.

This matters because —chemical equations to calculate reacting masses and vice versa determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —chemical equations to calculate reacting masses and vice versa to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Be able to use chemical equations to calculate volumes of gases and vice versa, using: i the concepts of amount of substance ii the molar volume of gases iii the expression pV = nRT for gases and volatile liquids.

Use —chemical equations to calculate volumes of gases and vice versa to connect the rule to the data and decision in the question.

This matters because —chemical equations to calculate volumes of gases and vice versa determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —chemical equations to calculate volumes of gases and vice versa to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Be able to calculate percentage yields and percentage atom economies (by mass) in laboratory and industrial processes, using chemical equations and experimental results Atom economy = molar mass of the desired product × 100% sum of the molar masses of all products.

Use —percentage yields and percentage atom economies (by mass) in laboratory and industrial processes to connect the rule to the data and decision in the question.

This matters because —percentage yields and percentage atom economies (by mass) in laboratory and industrial processes determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —percentage yields and percentage atom economies (by mass) in laboratory and industrial processes to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Percentage yields and percentage atom economies (by mass) in laboratory and industrial processes is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to determine a formula or confirm an equation by experiment, including evaluation of the data.

Use —determine a formula or confirm an equation by experiment to connect the rule to the data and decision in the question.

This matters because —determine a formula or confirm an equation by experiment determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —determine a formula or confirm an equation by experiment to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

CORE PRACTICAL 1 Measurement of the molar volume of a gas.

Use —core practical 1 measurement of the molar volume of a gas to connect the rule to the data and decision in the question.

This matters because —core practical 1 measurement of the molar volume of a gas determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —core practical 1 measurement of the molar volume of a gas to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —CORE PRACTICAL 1 Measurement of the molar volume of a gas is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to relate ionic and full equations, with state symbols, to observations from simple test-tube experiments, to include: i displacement reactions ii typical reactions of acids iii precipitation reactions.

Use —relate ionic and full equations, with state symbols, to observations from simple test-tube experiments, to include: i to connect the rule to the data and decision in the question.

This matters because —relate ionic and full equations, with state symbols, to observations from simple test-tube experiments, to include: i determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —relate ionic and full equations, with state symbols, to observations from simple test-tube experiments, to include: i to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.