Experiment - Preparation of Copper(II) Sulphate

Introduction

There are a number of different methods of making salts, such as the reaction of a metal with an acid. Copper metal, however, does not react with sulphuric acid and so another method must be used. In this experiment a basic copper compound (copper(II) oxide) will be reacted with sulphuric acid giving copper(II) sulphate as one of the products.

Method

Place 25 cm3 of dilute sulphuric acid in a 100 cm3 beaker and warm it gently over a Bunsen burner flame to about 50 oC. Add a small spatula measure of copper(II) oxide and stir, with a glass rod, until it dissolves. Then add a further spatula measure, with stirring and continue until a small quantity of copper(II) oxide is present in excess (How can you tell the copper(II) oxide is in excess?). Filter off the excess copper(II) oxide, allowing the filtrate to pass into an evaporating basin on a tripod and gauze, and heat it gently until half the liquid has evaporated. Leave the remaining liquid to crystallise.

Questions

(i) Write up the experiment fully as you do it, being careful to include all observations at the various stages.

(ii) Write a word and a balanced formula equation for this reaction.

(iii) How would you go about making copper(II) chloride crystals? Write a balanced formula equation for this reaction.