State the direction in which the position of equilibrium moves when the temperature of an equilibrium mixture is raised.

It moves in the endothermic direction, because that direction takes in energy and so opposes the rise in temperature.

The formation of ammonia from nitrogen and hydrogen is exothermic. Predict the effect of raising the temperature on the amount of ammonia in the equilibrium mixture.

The amount of ammonia falls, because the equilibrium shifts back towards nitrogen and hydrogen.

State the direction in which the position of equilibrium moves when the temperature of an equilibrium mixture is lowered.

It moves in the exothermic direction, because that direction releases energy and so opposes the fall in temperature.

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 Strong and weak acids The process of electrolysis, and molten ionic compounds Using electrolysis to extract metals Electrolysis of aqueous solutions Representation of reactions at electrodes as half equations

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 The energy change of reactions

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 Moles Amounts of substances in equations, and balancing using moles Limiting reactants

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 The effect of changing conditions on equilibrium The effect of changing concentration The effect of temperature changes on equilibrium The effect of pressure changes on 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 Alternative methods of extracting metals Life cycle assessment Ways of reducing the use of resources

The Rate and Extent of Chemical Change

The effect of temperature changes on equilibrium

3 things to know
Chemistry Paper 2

Overview

Why raising the temperature shifts an equilibrium in the endothermic direction and lowering it in the exothermic direction, the effect on yield for each type of forward reaction, ammonia and N₂O₄ as examples, and the compromise industrial temperature.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Explain why raising the temperature of a mixture at equilibrium disturbs it.

Key term

The forward reaction of a reversible reaction is endothermic. State the effect of raising the temperature on the relative amount of products at equilibrium.

Key term

The forward reaction of a reversible reaction is exothermic. State the effect of raising the temperature on the relative amount of products at equilibrium.

Questions from this subtopic

Each one with the model answer underneath.

1
State the direction in which the position of equilibrium moves when the temperature of an equilibrium mixture is raised.
Model answer
It moves in the endothermic direction, because that direction takes in energy and so opposes the rise in temperature.
2
Explain why raising the temperature of a mixture at equilibrium disturbs it.
Model answer
The forward and reverse reactions are no longer at the same rate, and the system shifts in the direction that absorbs energy until equilibrium is restored.
3
The forward reaction of a reversible reaction is endothermic. State the effect of raising the temperature on the relative amount of products at equilibrium.
Model answer
The relative amount of products increases.
4
The forward reaction of a reversible reaction is exothermic. State the effect of raising the temperature on the relative amount of products at equilibrium.
Model answer
The relative amount of products decreases.
5
The formation of ammonia from nitrogen and hydrogen is exothermic. Predict the effect of raising the temperature on the amount of ammonia in the equilibrium mixture.
Model answer
The amount of ammonia falls, because the equilibrium shifts back towards nitrogen and hydrogen.
6
State the direction in which the position of equilibrium moves when the temperature of an equilibrium mixture is lowered.
Model answer
It moves in the exothermic direction, because that direction releases energy and so opposes the fall in temperature.

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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.

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