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Edexcel International A Level Chemistry

Topic 1
Formulae, Equations
& Amount of Substance

Topic 1 builds the calculation and chemical language foundation for A Level Chemistry. It covers atoms, elements, ions, molecules, compounds, empirical formulae, molecular formulae, balanced equations, reacting masses, solution concentrations, gas volumes, percentage yield and atom economy.

Exam Unit
Unit 1
WCH11/01 – IAS
Specification Points
1.1 – 1.12
12 points covered
Topic Parts
5 parts
Revision notes available
Exam Board
Edexcel IAL
Pearson International

Revision Notes

Chemical language
Atoms,
Elements
& Molecules
atoms, ions, molecules, compounds and formulae
1
Available

Atoms, Elements and Molecules

Key definitions including atom, element, ion, molecule, compound, empirical formula and molecular formula.

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Equations and tests
Equations
& Reaction
Types
balanced, ionic and full equations
2
Available

Equations and Reaction Types

Balanced equations, ionic equations, state symbols, acid reactions and precipitation reactions.

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Amount of substance
Mole
Calculations
moles, Avogadro constant, mass and reacting quantities
3
Available

Mole Calculations

The mole, Avogadro constant, molar mass, reacting masses, percentage yield and atom economy.

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Formulae from data
Empirical
& Molecular
Formulae
formulae from experimental data and mass values
4
Available

Empirical and Molecular Formulae

Using experimental data, percentage composition and molar mass to calculate empirical and molecular formulae.

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Solutions and gases
Solutions
& Gases
concentration, gas volumes and pV = nRT
5
Available

Calculations with Solutions and Gases

Concentration in mol dm-3 and g dm-3, gas volumes, molar volume and the ideal gas equation.

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Specification Coverage

Topic 1 Formulae, Equations and Amount of Substance – Edexcel International A Level Chemistry

The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 1. Ideas from this topic are applied across all other units.

Chemical Language and Formulae

1.1
know the terms atom, element, ion, molecule, compound, empirical formula and molecular formula
1.4
understand relative atomic mass, relative molecular mass, relative formula mass, molar mass and parts per million.
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
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
The term relative formula mass should be used for compounds with giant structures.

The Mole and Core Calculations

1.2
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
1.5
calculate the concentration of a solution in mol dm-3 and g dm-3. Titration calculations are not required at this stage.
1.7
be able to use chemical equations to calculate reacting masses and vice versa, using the concepts of amount of substance and molar mass
1.8
be able to use chemical equations to calculate volumes of gases and vice versa.
i
the concepts of amount of substance
ii
the molar volume of gases
iii
the expression pV = nRT for gases and volatile liquids
1.9
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 ÷ sum of the molar masses of all products × 100%

Equations, Formulae and Experimental Data

1.3
write balanced full and ionic equations, including state symbols, for chemical reactions
1.6
be able to use experimental data to calculate empirical and molecular formulae
1.10
be able to determine a formula or confirm an equation by experiment, including evaluation of the data
1.12
be able to relate ionic and full equations, with state symbols, to observations from simple test-tube experiments.
ii
typical reactions of acids
iii
precipitation reactions

Core Practical and Further Suggested Practicals

1.11
CORE PRACTICAL 1
Measurement of the molar volume of a gas.
Practical
Further suggested practicals include preparing a salt and calculating percentage yield, determining a chemical formula by experiment, determining a chemical equation by experiment, and carrying out and interpreting simple test-tube reactions from 1.12.
i
preparation of a salt and calculating percentage yield of product, including the preparation of a double salt, such as ammonium iron(II) sulfate from iron, ammonia and sulfuric acid
ii
determine a chemical formula by experiment, such as the formula of copper(II) oxide by reduction
iii
determine a chemical equation by experiment, such as the reaction between lithium and water, or the reaction between magnesium and an acid
iv
carry out and interpret the results of simple test-tube reactions, as outlined in 1.12