**Precipitate Formation in the Reaction of Copper Sulphate and Hydrogen Sulphide**

**Introduction:**

When copper sulphate (CuSO4) reacts with hydrogen sulphide (H2S), a chemical reaction occurs. This reaction results in the formation of a precipitate. A precipitate is a solid substance that is formed when two liquids react and form an insoluble compound. In this case, the insoluble compound formed is known as copper sulphide (CuS).

**The Reaction:**

The reaction between copper sulphate and hydrogen sulphide can be represented by the following chemical equation:

CuSO4 + H2S -> CuS + H2SO4

**Explanation of the Reaction:**

1. Copper Sulphate (CuSO4):
Copper sulphate is a blue crystalline solid. In the reaction, it acts as the reactant.

2. Hydrogen Sulphide (H2S):
Hydrogen sulphide is a colorless gas with a strong odor of rotten eggs. It is a poisonous gas. In the reaction, it also acts as the reactant.

3. Copper Sulphide (CuS):
Copper sulphide is a black solid precipitate. It is insoluble in water. In the reaction, it is formed as a product.

4. Sulphuric Acid (H2SO4):
Sulphuric acid is a strong acid. It is formed as a byproduct of the reaction. It remains in solution and does not participate in the formation of the precipitate.

**Explanation of Precipitate Formation:**

In the reaction between copper sulphate and hydrogen sulphide, the copper ions (Cu2+) from copper sulphate combine with the sulphide ions (S2-) from hydrogen sulphide to form copper sulphide (CuS). Copper sulphide is insoluble in water and therefore, forms a solid precipitate.

The overall reaction can be written as:

Cu2+ + S2- -> CuS

As a result of this reaction, the blue color of copper sulphate disappears, and a black solid (copper sulphide) is formed. The formation of the black precipitate confirms the occurrence of the reaction.

**Conclusion:**

In the reaction between copper sulphate and hydrogen sulphide, the formation of a black solid precipitate (copper sulphide) confirms that a chemical reaction has taken place. The reaction can be represented by the equation: CuSO4 + H2S -> CuS + H2SO4.

C.CuS..