1 gram of a carbonate of a metal was dissolved in 25 ml of 1 N HCI. The resulting liquid required 5 ml of 1 N NaOH for neutralization. The eq. mass of metal carbonate is:

Options

A. 100
B. 30
C. 40
D. 50

Answer

To find the equivalent mass of the metal carbonate, we can follow these steps:

### Step 1: Calculate the amount of HCl that reacted
1. **Determine the total equivalents of HCl initially present:**
- Normality (N) of HCl = 1 N
- Volume (V) of HCl = 25 ml = 0.025 L
- Equivalents of HCl = N × V = 1 × 0.025 = 0.025 equivalents

2. **Determine the amount of NaOH used for neutralization:**
- Normality (N) of NaOH = 1 N
- Volume (V) of NaOH = 5 ml = 0.005 L
- Equivalents of NaOH = N × V = 1 × 0.005 = 0.005 equivalents

3. **Calculate the equivalents of HCl that reacted:**
- Equivalents of HCl reacted = Total equivalents of HCl - Equivalents of NaOH
- Equivalents of HCl reacted = 0.025 - 0.005 = 0.020 equivalents

### Step 2: Relate the equivalents of HCl to the metal carbonate
1. **Since the metal carbonate reacts with HCl, the equivalents of HCl reacted will equal the equivalents of the metal carbonate:**
- Therefore, equivalents of metal carbonate = 0.020 equivalents

### Step 3: Calculate the equivalent mass of the metal carbonate
1. **Use the formula for equivalent mass:**
- Equivalent mass = (mass of the substance) / (equivalents of the substance)
- Given mass of metal carbonate = 1 gram
- Equivalents of metal carbonate = 0.020 equivalents

2. **Substituting the values:**
- Equivalent mass = 1 g / 0.020 equivalents = 50 g/equivalent

### Conclusion
The equivalent mass of the metal carbonate is **50 g/equivalent**.

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