Hydrazine `N_(2)H_(4)` acts as a reducing agent. To prepare 100 ml of 2 N hydrazine solution, the weight required will be

Options

A. 6.4 g
B. 1.6 g
C. 3.2 g
D. 0.8 g

Answer

To solve the problem of preparing a 100 ml solution of 2 N hydrazine (N₂H₄), we need to follow these steps:

### Step-by-Step Solution:

1. **Determine the Valency Factor**:
- Hydrazine (N₂H₄) acts as a reducing agent and oxidizes to nitrogen (N₂).
- The oxidation state of nitrogen in N₂H₄ is +2 (let's denote it as X, so 2X - 4 = 0, which gives X = +2).
- The oxidation state of nitrogen in N₂ is 0.
- The change in oxidation state per molecule of N₂H₄ is 4 (from +2 to 0 for two nitrogen atoms).
- Therefore, the valency factor (n) = 4.

2. **Calculate the Equivalent Mass**:
- The molecular weight of hydrazine (N₂H₄) = 32 g/mol.
- The equivalent mass is calculated using the formula:
\[ \text{Equivalent mass} = \frac{\text{Molar mass}}{\text{Valency factor}} = \frac{32 \text{ g/mol}}{4} = 8 \text{ g/equiv} \]

3. **Use Normality to Find Gram Equivalents**:
- Normality (N) is defined as:
\[ N = \frac{\text{Number of gram equivalents}}{\text{Volume in L}} \]
- For 2 N solution in 100 ml (0.1 L):
\[ 2 = \frac{\text{Number of gram equivalents}}{0.1} \]
- Therefore, the number of gram equivalents = 2 × 0.1 = 0.2 equivalents.

4. **Calculate the Required Mass of Hydrazine**:
- The mass of hydrazine required can be calculated using the formula:
\[ \text{Mass} = \text{Number of gram equivalents} \times \text{Equivalent mass} \]
- Substituting the values:
\[ \text{Mass} = 0.2 \text{ equivalents} \times 8 \text{ g/equiv} = 1.6 \text{ g} \]

### Final Answer:
The weight of hydrazine required to prepare 100 ml of a 2 N solution is **1.6 grams**.