a scale of acidity or alkalinity, often shown to be between values of 0 and 14

a solution or paper which will change a different colour depending on pH of a solution

an electric device which measures pH and provides a value after being calibrated with reference samples

the concentration of hydrogen ions (H⁺) present in a solution; acids have a pH value less than 7

the concentration of hydroxide ions (OH⁻) present in a solution; alkalis have a pH value greater than 7

pH scale and indicators

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

By showing the colour change in universal indicator.

By measuring the temperature of the solution.

By indicating the volume of the solution.

How does the pH scale indicate whether a substance is acidic or basic?

What colour does methyl orange turn in acidic conditions?

Which indicator changes from colourless to pink in alkaline conditions?

How does litmus paper indicate a neutral solution?

It only shows one colour for all pH levels.

It provides a full range of colours but might not pinpoint the exact pH.

It cannot be used with strong acids or bases.

What is a limitation of using universal indicator?

Which of the following is common laboratory equipment used to measure pH?

What colour does litmus paper turn in an acidic solution?

Which ion's concentration is high in acidic solutions?

What should you always wear to protect your eyes in a laboratory?

Content guidance

Risk assessment required - chemicals

Risk assessment required - equipment

Adult supervision required

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

pH scale and indicators

Lesson outcome

Content guidance

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