The equivalent wieght of an acid is equal to

Options

A. Molecular weight x acidity
B. Molecular weight x basicity
C. molecular weight/basicity
D. molecular weight /acidity

Answer

To determine the equivalent weight of an acid, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Equivalent Weight**:
The equivalent weight of an acid is defined as the mass of the acid that can donate one mole of protons (H⁺ ions) in a reaction.

2. **Formula for Equivalent Weight**:
The formula for calculating the equivalent weight of an acid is:
\[ \text{Equivalent Weight} = \frac{\text{Molecular Weight}}{\text{Basicity}} \]
where:
- Molecular Weight is the sum of the atomic weights of all atoms in the acid.
- Basicity is the number of protons (H⁺ ions) that the acid can donate.

3. **Example Calculation**:
Let's calculate the equivalent weight of hydrochloric acid (HCl) and sulfuric acid (H₂SO₄) as examples.

- **For HCl**:
- **Molecular Weight**:
- Hydrogen (H) = 1.008 g/mol
- Chlorine (Cl) = 35.45 g/mol
- Total Molecular Weight of HCl = 1.008 + 35.45 = 36.458 g/mol
- **Basicity**: HCl can donate 1 proton (H⁺), so its basicity = 1.
- **Equivalent Weight**:
\[ \text{Equivalent Weight of HCl} = \frac{36.458}{1} = 36.458 \text{ g/equiv} \]

- **For H₂SO₄**:
- **Molecular Weight**:
- Hydrogen (H) = 1.008 g/mol (2 H atoms)
- Sulfur (S) = 32.07 g/mol
- Oxygen (O) = 16 g/mol (4 O atoms)
- Total Molecular Weight of H₂SO₄ = (2 × 1.008) + 32.07 + (4 × 16) = 98.086 g/mol
- **Basicity**: H₂SO₄ can donate 2 protons (H⁺), so its basicity = 2.
- **Equivalent Weight**:
\[ \text{Equivalent Weight of H₂SO₄} = \frac{98.086}{2} = 49.043 \text{ g/equiv} \]

4. **Conclusion**:
- For monobasic acids like HCl, the equivalent weight is equal to the molecular weight.
- For dibasic acids like H₂SO₄, the equivalent weight is half of the molecular weight.