Synthetic Inorganic Chemistry

62 WATER AND SOLUTION

ture, on paper towels. The double salt tends to effloresce, and the
crystals should be transferred to a stoppered bottle as soon as
they are dry.

QUESTIONS

1. Determine whether double salts can be prepared containing
   sodium sulphate and copper sulphate; potassium sulphate and
   copper sulphate.
   (a) Dissolve 1 gram of potassium sulphate and 2 grams of
   copper sulphate in 10 cc. of hot water. Pour the clear solution on
   a watch glass. When crystals have formed, see if they are all of
   the same kind (i.e., the double salt), or of two distinct kinds (the
   two simple salts).
   (6) Repeat the experiment using 1 gram of anhydrous sodium
   sulphate and 2 grams of copper sulphate. Account for your results.

PREPARATION 4

POTASSIUM-COPPER SULPHATE, K 2 SO4-CUSO4-6H 2 O

Read the preliminary discussion which precedes the preparation

of ammonium-copper sulphate, page 61.

Materials: potassium sulphate, K 2 SO 4 , 35 grams = 0.2 F.W.

copper sulphate, CuSO 4 -5H 2 O, 50 grams = 0.2 F.W.

Apparatus: 8-inch porcelain evaporating dish.

5-inch funnel and filter paper.

8-inch crystallizing dish,

iron ring and ring stand.

Bunsen burner.

Procedure: Prepare potassium-copper sulphate from potassium

sulphate and copper sulphate. Follow the procedure outlined in

the previous preparation. Determine the volume of water to be

used to give a saturated solution at 25°.

Solubility of the anhydrous salts in 100 grams water at 25°:

CuSO 4

K 2 SO 4

K 2 SO 4 -CuSO 4

23

12

11

grams

cc

cc