Salt Formed From Insoluble Base And Acid

Question 1

What is the method to make copper sulphate crystals?

Answer 1

1. Measure 40 cm3 sulfuric acid and put it into the 100 cm3 beaker.
2. Set up the Bunsen burner, tripod, gauze and heatproof mat. Put the beaker on the gauze and heat the acid gently until it is almost boiling. Turn off the Bunsen burner.
3. Remove the glass beaker from the tripod. Use the spatula to add a small amount of copper (II) oxide powder to the hot acid. Stir with the glass rod. The copper (II) oxide will disappear and
   the solution will turn clear blue.
4. Add some more copper (II) oxide and stir again.
5. Keep adding the copper (II) oxide until some of it remains after stirring.
6. Allow the apparatus to cool completely.
7. Set up the filter funnel and paper over the conical flask. Filter the contents of the beaker
8. Pour the filtrate from the conical flask into the evaporating basin.
9. Set up a water bath using the 250 cm3 beaker on the tripod and gauze.
10. Evaporate the filtrate gently using the water bath.
11. When crystals start to form, stop heating the water bath.
12. Pour the remaining solution into the crystallising dish.
13. Leave the crystallising dish in a cool place for at least 24 hours.
14. Remove the crystals from the concentrated solution with a spatula.
    Gently pat the crystals dry between two pieces of filter paper

Question 2

What is a salt?

Answer 2

An ionic compound made from a neutralisation reaction

Question 3

Why can solid copper not be used?

Answer 3

It won’t react with the acid

Question 4

Why is base added in excess?

Answer 4

To ensure the acid is fully reacted and there is none left meaning the crystals are pure

Question 5

What is the word equation for the reaction?

Answer 5

Copper oxide+sulfuric acid—>copper sulphate+water