In an experiment 2.65 g of zinc displaced 2.58 g of copper from copper sulphate solution. If equivalent weight of copper is 31.75, calculate that of zinc.

Answer

To calculate the equivalent weight of zinc based on the displacement of copper from copper sulfate solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Reaction**:
In the reaction, zinc displaces copper from copper sulfate. The reaction can be represented as:
\[ \text{Zn} + \text{CuSO}_4 \rightarrow \text{ZnSO}_4 + \text{Cu} \]
This indicates that zinc and copper are equivalent in terms of their ability to displace each other.

2. **Set Up the Equivalent Weight Equation**:
The equivalence of zinc is equal to the equivalence of copper. The formula for equivalent weight is:
\[ \text{Equivalent Weight} = \frac{\text{Mass}}{\text{Number of equivalents}} \]
Therefore, we can express the equivalence of zinc and copper as:
\[ \frac{\text{Mass of Zn}}{\text{Equivalent Weight of Zn}} = \frac{\text{Mass of Cu}}{\text{Equivalent Weight of Cu}} \]

3. **Substitute the Known Values**:
We know the following from the problem:
- Mass of zinc (Zn) = 2.65 g
- Mass of copper (Cu) = 2.58 g
- Equivalent weight of copper = 31.75 g

Plugging these values into the equation gives:
\[ \frac{2.65}{\text{Equivalent Weight of Zn}} = \frac{2.58}{31.75} \]

4. **Cross-Multiply to Solve for Equivalent Weight of Zinc**:
Rearranging the equation, we get:
\[ 2.65 \times 31.75 = 2.58 \times \text{Equivalent Weight of Zn} \]
Now calculate the left side:
\[ 2.65 \times 31.75 = 84.2375 \]
Therefore, we have:
\[ 84.2375 = 2.58 \times \text{Equivalent Weight of Zn} \]

5. **Isolate the Equivalent Weight of Zinc**:
Now, divide both sides by 2.58 to find the equivalent weight of zinc:
\[ \text{Equivalent Weight of Zn} = \frac{84.2375}{2.58} \approx 32.61 \text{ g} \]

### Final Answer:
The equivalent weight of zinc is approximately **32.61 g**.