Question

The method which cannot be used for the preparation of copper salts is:

• A. 1 (Action of acid on bases)
• B. 2 (Action of acid on carbonates)
• C. 3 (Action of acid on metals)
• D. 4 (Action of acid on sulphites)

Hint:

To make Copper(II) Sulphate in a lab, we typically react Copper(II) Oxide with hot dilute Sulphuric acid.

Answer 1

The Correct Option is C

To determine which method cannot be used for the preparation of copper salts, we should evaluate the reaction of acids with different substances and how they form salts. Let's examine each option:

1. Action of acid on bases: Acids react with bases to form salts and water. This is a neutralization reaction. For example, when hydrochloric acid (HCl) reacts with a base like copper hydroxide (Cu(OH)₂), it forms copper chloride (CuCl₂) and water.
2. Action of acid on carbonates: Acids react with carbonates to produce salts, water, and carbon dioxide gas. For example, when hydrochloric acid reacts with copper carbonate (CuCO₃), it forms copper chloride, water, and carbon dioxide.
3. Action of acid on metals: Acids typically react with metals to produce hydrogen gas and a salt, but copper does not react with most dilute acids to form salts as it is a less reactive metal. This inability to react under normal conditions prevents the formation of copper salts through this method. Therefore, this method is not generally applicable for preparing copper salts.
4. Action of acid on sulphites: Acids react with sulphites to produce salts, water, and sulphur dioxide gas. This method can be used to prepare salts from reactions involving sulphites.

From the explanation above, it is clear that option 3, the action of acid on metals, cannot be used for the preparation of copper salts. This is because copper is not reactive enough to undergo a displacement reaction with dilute acids under normal conditions to form copper salts.

Therefore, the correct answer is option 3 (Action of acid on metals).