Question

how can you prepare an insoluble base

Answer 1

If the base is insoluble, then an extra step is needed to form a salt. You add the base to the warm acid until no more will dissolve and you have some base left over – this is called an 'excess'. You filter the mixture to remove the excess base, and then evaporate the water in the filtrate to leave the salt behind.

Answer 2

Insoluble salts are prepared by precipitation via a double decomposition method, as shown below:

M

1

A(aq)+

M

2

B(aq)→

M

1

B(aq)

+

M

2

A(aq)

M1A(aq)+M2B(aq)→M1B(aq)+M2A(aq)

Notice that A and B are swapped.

You may follow the following procedures to prepare insoluble salts:

1) Mix the solutions.

2) Filter out the precipitate.

3)Wash residue with deionised water.

4)Dry precipitate between sheets of filter paper.