Page 135 - Chemistry_Form_2

Chemistry
for Secondary Schools

Reactions of acids with insoluble bases

Reactions of acids with insoluble bases result in the formation of soluble salts.
For example, insoluble bases of zinc oxide and copper(II) oxide react with acids
to form soluble salts like zinc sulfate, copper(II) sulfate, copper(II) chloride, and
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water.

Activity 5.9

Aim: To prepare copper(II) chloride

Requirements: 100-mL measuring cylinder, tripod stand, 250-mL beaker,
glass rod, evaporating dish, wire gauze, filter papers, funnel, heat
source, 2 M hydrochloric acid solution, and copper(II) oxide,

Procedure

1. Pour about 50 cm of 2 M hydrochloric acid into a beaker and heat gently.
3
2. Dissolve some copper(II) oxide little by little in the hot acid and stir for
some time until the metal oxide is in excess.
3. Filter off the solid and heat the filtrate until it approaches to dryness.

Questions
1. What chemical reaction took place in this experiment? Explain with a

balanced chemical equation.
2. Why was it necessary to use hot hydrochloric acid in the reaction with
copper(II) oxide?
3. Why did you heat the fitrate?
4. What is the colour of the product formed in Step 3?

Reactions of acids with metal carbonates

Most metal carbonates such as calcium carbonate, copper(II) carbonate and
potassium carbonate react with acids to produce salt, water and carbon dioxide
gas as shown in the following equation:

128 Student’s Book Form Two

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