### Acids, Bases and Salts Question 1

1. Calcium sulphate can be formed by the reaction between calcium carbonate and solution X. Two other substances are produced in this reaction.
1. Name solution X. [1]
2. Name the other two products. [2]
3. Name the type of reaction that occur between calcium carbonate and X. [1]
4. To prepare a sample of calcium sulphate, excess calcium carbonate has to be added to solution X.

Explain why calcium carbonate should be in excess. [1]

5. Name the process that is used to separate the excess calcium carbonate from calcium sulphate solution. [1]
2. The strength of an acid or a base can be determined using the pH scale.
1. State the range of the pH scale. [1]
2. What is the pH value of a neutral substance. [1]
3. List two properties of alkaline substance. [2]

### Solution 1

1. Solution X is sulphuric acid.

because the salt formed is a sulphate.

2. Carbon dioxide and Water

(When carbonates react with acids, the products are salt, carbon dioxide and water)

3. Neutralisation.

Every reaction between an acid and a base (or alkali) or an acid and a carbonate is called a neutralisation reaction.

4. Calcium carbonate should be in excess in order to make sure that all acid has reacted.
5. Filtration.

because the excess calcium carbonate is insoluble once the reaction is finished

1. The strength of an acid or a base can be determined using the pH scale.
1. 0 to 14
2. 7
3. the pH scale is a measurement the acidity or alkaline of a substance based on a scale of 0 to 14. Acids have a pH value less than 7, bases and alkalis have a pH value greater than 7 and neutral substances have a pH of 7.

• They turn litmus paper blue
• They neutralise acids to produce a salt and water.
2. Metal oxides are bases and soluble bases are called alkalis (alkaline substances). So the chemical properties of bases and alkalis are the same.

#### Sydney Chako

Mathematics, Chemistry and Physics teacher at Sytech Learning Academy. From Junior Secondary School to Tertiary Level Engineering Mathematics and Engineering Science.

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