4.4.2.3 - Soluble salts

How can soluble salts be made from acids?

Soluble salts can be made from acids by reacting them with solid insoluble substances (bases)

Give some substances that can react with acids to produce soluble salts.

Any solid insoluble substances like :

• metals

• metal oxides

• metal hydroxides

• metal carbonates

Describe the process of producing soluble salts.

1. Gently warm the dilute acid using a Bunsen burner - then turn the bunsen burner off

2. Add the insoluble base to the acid a bit at a time - until the insoluble base is in excess (so no more reacts)

3. When this occurs, even after stirring, the excess insoluble base will sink to the bottom of the flask

4. Filter out the excess solid to get the salt solution - using a funnel from filter paper

5. Then gently heat the salt solution using an electric heater to the the point of crystallisation

6. After this leave the solution to dry.

7. This should produce pure, solid crystals of the salt

Salt solutions can be ___________ to produce solid salts

Salt solutions can be crystallised to produce solid salts

Why is the insoluble base added in excess?

To ensure that all the acid has reacted to produce a salt

Why do add the insoluble base in excess rather than the acid in excess?

The excess insoluble base can be filtered off - making it’s separation easier than the acids would be