When a substance dissolves in a liquid, it is described as soluble in that liquid.

any reactant present in a greater amount than is necessary to completely react with the limiting reactant

a technique to separate insoluble solids from a liquid by passing the mixture it is in through a filter

a process that forms solid crystals from a saturated solution by evaporating the solvent

Making a pure dry sample of a soluble salt

Combined science

In the Electrolysis unit, pupils will build on their understanding of chemical reactions to explore the process of electrolysis and its applications.

In the Acids and Bases unit, pupils learned about the properties of acids, bases, and alkalis, and the reactions between them to form salts and water.

This unit explores empirical formulae, balanced chemical and ionic equations, gas identification, acid reactions, and pH as a measure of hydrogen ion concentration. It covers separation techniques and focuses on planning experiments, accurate measurements, safety, and communicating findings.

Making salts

Physical activity and equipment requiring safe use

Reactions between an acid and a metal, or between an acid and certain metal compounds (like hydroxide, oxide or carbonate), are all types of {{}} reactions.

crystallising the soluble salt from a solution

filtering to remove any excess insoluble metal oxide

neutralising the acid with the insoluble metal oxide

reducing the temperature of the reactant mixture

An insoluble metal oxide reacts with an acid to make a soluble salt. What are the main steps, in any order, needed to make pure crystals of the soluble salt.

add one spatula at a time of powdered metal oxide to the acid and stir

stop when some of the metal oxide does not react

gently heat the mixture to allow more metal oxide to react with the acid

if needed, add more spatulas of metal oxide until it does not react again

use pH paper to check that the solution is neutral

An insoluble metal oxide reacts with an acid to make a soluble salt. Put each step in the correct order to describe how a metal oxide is reacted with an acid, making sure all the acid has reacted.

The undissolved impurity in a salt solution that remains in filter paper after filtration is called the {{}}.

light a Bunsen burner and turn the gas tap down to give a small yellow flame

open the air hole to get a small blue flame

use it to gently heat the solution in a evaporating dish over a water bath

remove the Bunsen burner each time the solution bubbles vigorously

replace the Bunsen burner, as necessary, to evaporate more water

stop heating when there is still a little water left

the rest of the water should evaporate as the evaporating dish cools down

Put each step in the correct order to describe how to obtain crystals of salt from a pure salt solution.

the property of a substance that dissolves in a liquid

the reactant left over after a reaction is complete

a technique for separating insoluble solids from a liquid

forming solid crystals from a saturated solution by evaporation

the reactant that is fully used up during a reaction

Match these key terms to the correct definitions.

How can you increase the concentration of a solution?

to separate insoluble solids from a liquid

to change the chemical composition of a mixture

metal carbonate + acid → salt + water + carbon dioxide

metal + water → metal hydroxide + hydrogen

Which of the following equations represent neutralisation reactions used for making salts?

Match each salt with the reactants that can be used to make it.

a solution where no more solute can dissolve

a solution that has evaporated completely

a solution that changes colour with more solute

the solute evaporates leaving the solvent

the solvent dissolves more solute to form crystals

solid crystals form by removing the solvent

the temperature of the solution decreases

Content guidance

Risk assessment required - chemicals

Risk assessment required - equipment

Adult supervision required

This lesson will be removed by end of Summer Term 2025.

Making a pure dry sample of a soluble salt

Lesson outcome

Content guidance

This lesson will be removed by end of Summer Term 2025.