Science - Practical Assessment (Acids and Bases)

Acids and Bases

Aim:

To measure the pH of several solids and liquids using Universal indicator solution and a pH pen.

Equipment:

• Spotting tile
• Universal indicator solution
• A few solid and liquid samples
• pH pen

Method:

1. Take two samples of each solid and liquid to be tested and arrange on your spotting tile. If it is a solid, add a drop of water.

2. Place one drop of Universal indicator on one of each sample.

3. Use the pH pen to measure the pH of the other samples.

Results:

Substance	Colour with pH	Description	pH Meter reading	Description
Eg. Substance A	Pale blue	Weak base	8.3	Weak base
Sugar	Blue/green	Weak base	6.2	Weak acid
Lux flakes	Light green	Weak acid	9.4	Weak base
Detergent	Pale yellow/green	Neutral	6.9	Very weak acid
Toothpaste	Blue	Strong base	5.7	Weak acid
Fruit juice	Pale red	Weak acid	1.9	Strong acid
Window cleaner	Blue	Base	6.7	Weak acid
Citric acid	Yellow/Orange	Weak Acid	6.3	Weak acid
Cheesels	Blue	Base	12.3	Strong base