Producing a soluble salt from an acid and an insoluble base

Question 1

How do we add the excess insoluble copper oxide to sulphuric acid?

Answer 1

Keep adding more copper oxide and stirring until the black powder no longer disappears after stirring

Question 2

When reacting insoluble copper oxide with dilute sulphuric acid, why is excess copper oxide used?

Answer 2

To ensure that all the sulphuric acid reacts. The excess copper oxide can be filtered out as it doesn’t dissolve

Question 3

What two final steps are needed to obtain the pure soluble salt?

Answer 3

Filtration and crystallisation

Question 4

During crystallization, why isn’t the copper sulphate solution heated directly?

Answer 4

The liquid would bubble and spit, and the water would evaporate too quickly leaving small crystals.

Question 5

How do you indirectly heat the copper sulphate solution during crystallisation?

Answer 5

Place the evaporating basin containing the solution on a beaker half filled with water. Heat the beaker and the basin with a bunsen burner

Question 6

What is residue?

Answer 6

The solid left in the filter paper after filtration

Question 7

What is a filtrate?

Answer 7

The liquid passing through the filter paper