pH scale and universal indicator solution
I can measure the pH of an acid or alkali using the pH scale.
pH scale and universal indicator solution
I can measure the pH of an acid or alkali using the pH scale.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- Most acids and alkalis are colourless solutions, so indicators can be used to identify them.
- pH stands for ‘potential of hydrogen’ and acids contain hydrogen.
- The higher the concentration of hydrogen, the lower the pH.
- The pH scale goes up and down in factors of ten, so an acid of pH 2 is ten times more acidic than pH 3.
- A low pH means acidic, a high pH means alkaline and solutions with a pH of 7 are neutral.
Keywords
PH scale - A scale from 1 to 14 used to measure the acidity or alkalinity of solutions. pH7 is for neutral solutions.
Acidic - A solution that has a pH of less than 7.
Alkaline - A solution that has a pH of more than 7.
Neutral solution - A solution that has a pH of 7.
Concentration - The amount of chemical dissolved in a certain volume of solution.
Common misconception
The difference between concentrated and dilute vs strong and weak when referring to acids and alkalis (not covered in this lesson).
For acids and alkalis concentration is the amount of hydrogen dissolved in a certain volume of solution. The higher the concentration, the lower the pH. Strong and weak refer to the ability of an acid to release hydrogen (not covered in lesson).
To help you plan your year 9 science lesson on: pH scale and universal indicator solution, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 9 science lesson on: pH scale and universal indicator solution, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 3 science lessons from the Acids and bases unit, dive into the full secondary science curriculum, or learn more about lesson planning.
Equipment
Universal indicator paper or solution, test tubes, test tube racks, plastic pipettes, spotting tiles, indicator charts.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
Lesson video
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Starter quiz
6 Questions
A solution with a pH of less than 7.
A soluble base with a pH greater than 7.
A substance which reacts with an acid to form a salt and water.
Exit quiz
6 Questions
Measures the acidity or alkalinity of solutions.
A solution that has a pH of 7.
A solution with a pH of more than 7.
A solution with a pH of less than 7.