How many grams of dibasic acid (mol. weight 100) should be present in 200 mL of the aqueous solution to give strength 0.1 N?

Options

A. 1g
B. 0.1g
C. 10g
D. 2g

Explanation

To determine how many grams of a dibasic acid (molecular weight = 100) should be present in 200 mL of an aqueous solution to achieve a strength of 0.1 N, we can follow these steps:

### Step 1: Understand Normality
Normality (N) is defined as the number of equivalents of solute per liter of solution. For a dibasic acid, which can donate two protons (H⁺ ions), the basicity is 2.

### Step 2: Convert Volume from mL to L
We need to convert the volume of the solution from milliliters to liters:
\[ \text{Volume in L} = \frac{200 \text{ mL}}{1000} = 0.2 \text{ L} \]

### Step 3: Calculate Equivalent Weight
The equivalent weight of the dibasic acid can be calculated using the formula:
\[ \text{Equivalent Weight} = \frac{\text{Molecular Weight}}{\text{Basicity}} \]
Given that the molecular weight is 100 and the basicity is 2:
\[ \text{Equivalent Weight} = \frac{100}{2} = 50 \text{ g/equiv} \]

### Step 4: Use the Normality Formula
The formula for normality is:
\[ N = \frac{\text{Number of Gram Equivalents of Solute}}{\text{Volume of Solution in L}} \]
Rearranging this formula to find the mass of the solute gives:
\[ \text{Mass} = N \times \text{Equivalent Weight} \times \text{Volume in L} \]
Substituting the values:
\[ \text{Mass} = 0.1 \, \text{N} \times 50 \, \text{g/equiv} \times 0.2 \, \text{L} \]

### Step 5: Calculate the Mass
Now, we can calculate the mass:
\[ \text{Mass} = 0.1 \times 50 \times 0.2 = 1 \text{ g} \]

### Conclusion
Therefore, the mass of the dibasic acid required is **1 gram**.

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