State what is meant by a reversible reaction.

It is a reaction in which the products can react together to produce the original reactants again.

For the reversible reaction A + B ⇌ C + D, describe the forward and the reverse reaction.

In the forward reaction A and B react to form C and D, and in the reverse reaction C and D react to form A and B.

Explain how heating and then cooling can drive a reversible reaction first one way and then the other.

Heating drives the reaction in the direction that takes in energy, and cooling allows the opposite direction, which releases energy, to take over.

AQA GCSE Combined Science Chemistry 8464

Atomic Structure and the Periodic Table

Topic overview Atoms, elements and compounds Word equations, symbols and balanced equations Mixtures From the plum pudding model to the nuclear model Bohr, Chadwick and the modern model of the atom Relative electrical charges of subatomic particles Size and mass of atoms Relative atomic mass and electronic structure The periodic table Development of the periodic table Metals and non-metals Group 0 Group 1 Group 7

Bonding, Structure, and the Properties of Matter

Topic overview Chemical bonds, including metallic bonding Ionic bonding Ionic compounds Covalent bonding and how it is represented The three states of matter and changes of state Predicting state, state symbols, and the limits of the particle model Properties of ionic compounds Properties of small molecules Polymers and giant covalent structures Properties of metals and alloys, and why metals conduct Diamond and graphite Graphene and fullerenes

Chemical Analysis

Topic overview Pure substances Formulations Chromatography Tests for hydrogen, oxygen, carbon dioxide and chlorine

Chemical Changes

Topic overview The reactivity series Metal oxides, extraction, and redox in terms of electrons Acids reacting with metals, neutralisation and salts Soluble salts The pH scale and neutralisation The process of electrolysis, and molten ionic compounds Using electrolysis to extract metals Electrolysis of aqueous solutions

Chemistry of the Atmosphere

Topic overview The Earth's early atmosphere How oxygen increased and carbon dioxide decreased The gases in today's atmosphere, and which are greenhouse gases Human activities which contribute to an increase in greenhouse gases in the atmosphere Global climate change and carbon footprints Atmospheric pollutants from fuels, and their effects

Energy Changes

Topic overview Exothermic and endothermic reactions Everyday uses, and investigating temperature change Reaction profiles

Organic Chemistry

Topic overview Crude oil, hydrocarbons and alkanes Fractional distillation and petrochemicals Properties of hydrocarbons Cracking, and testing alkenes with bromine water Why cracking is useful, and equations for it

Quantitative Chemistry

Topic overview Conservation of mass and balanced chemical equations Relative formula mass and concentration of solutions Mass changes when a gas is involved, and measurement uncertainty

The Rate and Extent of Chemical Change

Topic overview Measuring the mean rate of a reaction Rate from graphs, and the gradient of a tangent Factors which affect the rates of chemical reactions Collision theory and activation energy Catalysts Reversible reactions and dynamic equilibrium

Using Resources

Topic overview Using the Earth's resources and sustainable development Producing potable water in the UK Desalination, and analysing water samples Waste water treatment Life cycle assessment Ways of reducing the use of resources

The Rate and Extent of Chemical Change

Reversible reactions and dynamic equilibrium

3 things to know
Chemistry Paper 2

Overview

Reversible reactions and the ⇌ symbol, forward and reverse reactions and changing direction by altering conditions, heating and rehydrating copper sulfate, equal energy transferred in each direction, the closed system needed for equilibrium, and equilibrium as forward and reverse reactions continuing at the same rate.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Describe the symbol written between the reactants and the products of a reversible reaction.

Key term

In the reversible reaction A + B ⇌ C + D, name the substances that are the products of the reverse reaction.

Key term

State what has to be altered to change the direction in which a reversible reaction goes.

Questions from this subtopic

Each one with the model answer underneath.

1
State what is meant by a reversible reaction.
Model answer
It is a reaction in which the products can react together to produce the original reactants again.
2
Describe the symbol written between the reactants and the products of a reversible reaction.
Model answer
Two half arrows pointing in opposite directions, ⇌, in place of the single arrow.
3
For the reversible reaction A + B ⇌ C + D, describe the forward and the reverse reaction.
Model answer
In the forward reaction A and B react to form C and D, and in the reverse reaction C and D react to form A and B.
4
In the reversible reaction A + B ⇌ C + D, name the substances that are the products of the reverse reaction.
Model answer
A and B.
5
State what has to be altered to change the direction in which a reversible reaction goes.
Model answer
The conditions, such as the temperature, must be changed.
6
Explain how heating and then cooling can drive a reversible reaction first one way and then the other.
Model answer
Heating drives the reaction in the direction that takes in energy, and cooling allows the opposite direction, which releases energy, to take over.

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Atomic Structure and the Periodic Table

Bonding, Structure, and the Properties of Matter

Chemical Analysis

Chemical Changes

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AMolecular size controls boiling point, viscosity and flammability.

BSmall molecules make gases and petrol that ignite easily.

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