Required amount of crystalline oxalic acid (eq. wt. = 63 ) to prepare `(N)/(10)`, 250 ml oxalic acid solution is

Options

A. 0.158g
B. 1.575 g
C. 15.75g
D. 6.3g

Answer

To find the required amount of crystalline oxalic acid to prepare a \( \frac{N}{10} \) (0.1 N), 250 ml oxalic acid solution, we can follow these steps:

### Step 1: Understand Normality
Normality (N) is defined as the number of equivalents of solute per liter of solution. In this case, we have a \( \frac{N}{10} \) solution, which is equivalent to 0.1 N.

### Step 2: Determine the Volume of Solution
The volume of the solution is given as 250 ml. We need to convert this volume into liters for our calculations:
\[ \text{Volume in liters} = \frac{250 \text{ ml}}{1000} = 0.25 \text{ L} \]

### Step 3: Calculate the Number of Equivalents
Using the formula for normality:
\[ \text{Normality (N)} = \frac{\text{Number of equivalents}}{\text{Volume in L}} \]
We can rearrange this to find the number of equivalents:
\[ \text{Number of equivalents} = \text{Normality} \times \text{Volume in L} = 0.1 \times 0.25 = 0.025 \text{ equivalents} \]

### Step 4: Determine the Equivalent Weight of Oxalic Acid
The equivalent weight (eq. wt.) of oxalic acid is given as 63 g. This is calculated using the formula:
\[ \text{Equivalent weight} = \frac{\text{Molecular weight}}{\text{n-factor}} \]
For oxalic acid (H₂C₂O₄), the n-factor is 2 (since it can donate 2 protons). The molecular weight of oxalic acid is 126 g/mol, so:
\[ \text{Equivalent weight} = \frac{126}{2} = 63 \text{ g} \]

### Step 5: Calculate the Required Weight of Oxalic Acid
Now, we can find the weight of oxalic acid needed using the formula:
\[ \text{Weight (Wb)} = \text{Number of equivalents} \times \text{Equivalent weight} \]
Substituting the values we have:
\[ \text{Weight (Wb)} = 0.025 \text{ equivalents} \times 63 \text{ g/equivalent} = 1.575 \text{ g} \]

### Conclusion
The required amount of crystalline oxalic acid to prepare a \( \frac{N}{10} \), 250 ml oxalic acid solution is **1.575 grams**.

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