Equivalent weight of an acid

Options

A. depends on the reaction involved
B. depends upon the number of oxygen atoms present
C. is always constant
D. None of the above

Answer

To calculate the equivalent weight of an acid, follow these steps:

### Step-by-Step Solution

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

2. **Identify the Molar Mass of the Acid**:
Determine the molar mass of the acid you are working with. The molar mass is the mass of one mole of the substance, typically expressed in grams per mole (g/mol).

3. **Determine the Basicity of the Acid**:
Basicity refers to the number of ionizable hydrogen atoms present in one molecule of the acid. For example, in hydrochloric acid (HCl), there is one ionizable hydrogen atom, so its basicity is 1. In sulfuric acid (H₂SO₄), the basicity is 2 because it has two ionizable hydrogen atoms.

4. **Calculate the Equivalent Weight**:
Use the formula:
\[ \text{Equivalent Weight} = \frac{\text{Molar Mass}}{\text{Basicity}} \]
Substitute the molar mass and basicity into the formula to find the equivalent weight.

5. **Consider the Reaction Context (if applicable)**:
If the acid is involved in a specific chemical reaction, the equivalent weight may also depend on how many hydrogen ions are replaced or donated in that reaction. This means you need to analyze the reaction to determine the effective basicity in that context.

### Example Calculation
- For hydrochloric acid (HCl):
- Molar mass of HCl = 36.46 g/mol
- Basicity = 1 (since it has one ionizable hydrogen)
- Equivalent weight = 36.46 g/mol ÷ 1 = 36.46 g