How many gram of dibasic acid (mol. Mass=200) should be present in 100ml of the aqueous solution to make it 0.1 N?

Options

A. 1 g
B. 2 g
C. 10 g
D. 20 g

Answer

To determine how many grams of dibasic acid (molecular mass = 200 g/mol) are needed to prepare a 100 mL aqueous solution with a normality of 0.1 N, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Normality and Dibasic Acid:**
- Normality (N) is a measure of concentration equivalent to molarity (M) multiplied by the number of equivalents (n factor).
- For a dibasic acid, the n factor is 2 because it can donate 2 H⁺ ions per molecule.

2. **Calculate Molarity from Normality:**
- Given that the normality is 0.1 N and the n factor is 2, we can find the molarity (M) using the formula:
\[ M = \frac{N}{n} \]
- Substituting the values:
\[ M = \frac{0.1}{2} = 0.05 \, \text{M} \]

3. **Use the Molarity to Find the Number of Moles:**
- Molarity is defined as the number of moles of solute per liter of solution:
\[ M = \frac{\text{Number of moles}}{\text{Volume in liters}} \]
- The volume of the solution is 100 mL, which is equal to 0.1 L. Rearranging the formula gives:
\[ \text{Number of moles} = M \times \text{Volume in liters} = 0.05 \times 0.1 = 0.005 \, \text{moles} \]

4. **Convert Moles to Grams:**
- To find the mass (in grams) of dibasic acid, use the formula:
\[ \text{Mass} = \text{Number of moles} \times \text{Molar mass} \]
- Substituting the values:
\[ \text{Mass} = 0.005 \, \text{moles} \times 200 \, \text{g/mol} = 1 \, \text{gram} \]

### Final Answer:
1 gram of dibasic acid should be present in 100 mL of the aqueous solution to make it 0.1 N.