4.7 describe experiments to prepare soluble salts from acids

Dilute sulphuric acid is added to an excess of magnesium.
Mg + H2SO4 > MgSO4 + H2
The left over magnesium is filtered off and the mixture boiled down slowly to concentrate.
When it is cooled, crystals will form, these can be blotted dry with a piece of paper.

This can be done with other metals and acids:

Nitric, sulphuric and hydrochloric acids make soluble salts with most metals.

ammonium, potassium and sodium make soluble salts with acids