1. Lesson Starter Tell me what is on the board – pH scale
What is the purpose of the pH scale? – To tell us how strong or weak an acid/alkali is
What do we use in order to see these colours?- indicator
What do the different colours tell us? Example
Household examples

2. Learning Intention
To learn about neutralisation and how we can use it to prevent the damage of acids/alkalis

3. Experiment: challenge
20 minutes to create a test tube rainbow
We know that different acids and alkalis have different pHs and so would create different colours but your challenge is to create the rainbow using just one acid and one alkalki
Best rainbow gets a prize

4. Experiment: Challenge
Apparatus
Test tube rack
5 test tubes
Acid
Alkali
Universal indicator
pH scale
Instructions
Place 2 fingers of water in each test tube
Place 5 drops of universal indicator in each test tube
The rest is for you to work out!
I’ve given a few instructions to start off, the rest you will need to work out! Don’t forget you are using harmful substances so will need to be wearing goggles.
Start the countdown and after the time is up get all the teams to bring their rainbows to the front with their name on it for judging. Award the points and tidy up the experiment.

5. Neutralisation
Add Alkali
Add Acid
Acids
Alkalis

6. How could you stop the pain?
Bee sting- pH 3
Wasp sting- pH 9