Background

In this experiment you will investigate the properties of three substances in the kitchen to determine if they are acids or alkalis.

Acids have a sour taste. In high concentrations acids can burn your skin and other living tissue. But the acids you are working with in the kitchen have very low concentrations and safe to touch. Examples of laboratory acids are hydrochloric acid, sulphuric acid and nitric acid.

Alkalis have a bitter taste and feel slippery when you touch them. Alkalis in high concentrations can burn your skin or other living tissue too. But the alkalis in your kitchen have low concentrations and are safe to touch. One common alkali in laboratories is sodium hydroxide.

You will need:

• 1 lemon or lemon juice
• vinegar
• dish washing soap (liquid soap for hand washing works too)

What to do:

1. Copy the table below.

2. If you have a lemon instead of lemon juice you need to squeeze it now and collect some juice from it for your experiment.
3. Look at the lemon juice, vinegar and dish washing soap and record in your table what they look like.
4. In turns drop a bit of each of the substances on your hand and test what they feel like. Record it in your table.
5. Now taste the lemon juice and the vinegar. Record what they taste like in your table. You do not have to taste the dish washing soap.

Questions

1. Based on your data decide which substances are acids and which are alkalis and record it in your table. Use the text in the introduction to help you. It gives you information about the properties of acids and alkalis.
2. What do you expect the dish washing soap would taste like? Why?
3. Name two properties of acids.
4. Name three properties of alkalis.
5. Name two laboratory acids.
6. Name one laboratory alkali.
7. Which other acids and alkalis do you know that you have in the kitchen or the home?