0.98 g of the metal sulphate was dissolved in water and excess of barium chloride was added. The precipitated barium sulphate weighted 0.95 g. Calculate the equivalent weight of the metal.

Answer

To solve the problem of calculating the equivalent weight of the metal from the given data, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Mass of metal sulfate (M) = 0.98 g
- Mass of precipitated barium sulfate (BaSO₄) = 0.95 g

2. **Calculate the Molar Mass of Barium Sulfate (BaSO₄):**
- Molar mass of Ba = 137.33 g/mol
- Molar mass of S = 32.07 g/mol
- Molar mass of O = 16.00 g/mol (4 oxygen atoms)
- Molar mass of BaSO₄ = 137.33 + 32.07 + (4 × 16.00) = 137.33 + 32.07 + 64.00 = 233.40 g/mol

3. **Calculate the Mass of Sulfate (SO₄²⁻) in the Precipitate:**
- Molar mass of sulfate (SO₄²⁻) = 32.07 + (4 × 16.00) = 32.07 + 64.00 = 96.07 g/mol
- The mass of sulfate in the precipitate can be calculated using the ratio of the molar masses:
\[ \text{Mass of SO₄²⁻} = \left(\frac{\text{Molar mass of SO₄²⁻}}{\text{Molar mass of BaSO₄}}\right) \times \text{Mass of BaSO₄} \]
\[ \text{Mass of SO₄²⁻} = \left(\frac{96.07}{233.40}\right) \times 0.95 \text{ g} \approx 0.39 \text{ g} \]

4. **Calculate the Mass of the Metal:**
- The mass of the metal can be calculated by subtracting the mass of sulfate from the total mass of the metal sulfate:
\[ \text{Mass of metal} = \text{Mass of BaSO₄} - \text{Mass of SO₄²⁻} \]
\[ \text{Mass of metal} = 0.95 \text{ g} - 0.39 \text{ g} = 0.56 \text{ g} \]

5. **Calculate the Equivalent Weight of the Metal:**
- The equivalent weight of the metal can be calculated using the formula:
\[ \text{Equivalent weight} = \frac{\text{Mass of metal}}{\text{n}} \]
- Here, \( n \) is the number of moles of sulfate ions (which is 1 for SO₄²⁻).
- Since we have 0.56 g of the metal, the equivalent weight of the metal is:
\[ \text{Equivalent weight} = \frac{0.56 \text{ g}}{1} = 0.56 \text{ g/equiv} \]

### Final Answer:
The equivalent weight of the metal is **0.56 g/equiv**.