What Colour Is It?

To be able to use trial and improvement to produce different colours. Indicator Challenge Learning Objective: To be able to use trial and improvement to produce different colours.

Indicators can change colour Universal indicator can have lots of different colours...

Your challenge Make three solutions that will look like traffic lights when you add universal indicator.

How successful were you? All students should be able to mix two colours. Most students should be able to explain what they need to do to get the third colour right. Some students should be able to mix all three parts of the traffic light. 5

Your challenge Make three solutions that will look like traffic lights when you add indicator. You will need to record your ingredients each time you try because for the final test you will have to make the solutions without checking the colour

Trial and Improvement records: Volume of water (cm3) Name of acid or alkali Volume of acid or alkali (drops) Colour pH Improvement needed 5 sulphuric acid 1 yellow 6 more acid The key to this challenge is to work carefully and measure accurately!!!!!

Trial and Improvement records: Volume of water (cm3) Name of acid or alkali Volume of acid or alkali (drops) Colour pH Improvement needed 10 nitric acid 1 yellow 6 more acid When you think you have finished, test your three final recipes. Have you made the traffic light colours?

How successful were you? All students should be able to mix two colours. Most students should be able to explain what they need to do to get the third colour right. Some students should be able to mix all three parts of the traffic light.

How could you use these colour changes? Neutralisation reactions: acid + alkali a salt + water Nitric + potassium potassium + water acid hydroxide nitrate . How much alkali would be needed to neutralise 10cm3 of hydrochloric acid?