What amount of oxalic acid is required to prepare 250 mL 0.1 N solution (Given : molecular mass of oxalic acid = 126) ?

Answer

To determine the amount of oxalic acid required to prepare a 250 mL 0.1 N 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. For oxalic acid (H2C2O4), which can donate two protons (H+), the normality is twice the molarity.

### Step 2: Convert Volume to Liters
The volume of the solution is given as 250 mL. We need to convert this to liters:
\[ \text{Volume in liters} = \frac{250 \text{ mL}}{1000} = 0.25 \text{ L} \]

### Step 3: Relate Normality to Molarity
Using the relationship between normality and molarity:
\[ \text{Normality (N)} = \text{Molarity (M)} \times \text{Basicity (x)} \]
For oxalic acid, the basicity (x) is 2 (since it can donate 2 protons). Thus:
\[ 0.1 \text{ N} = \text{Molarity (M)} \times 2 \]
From this, we can find the molarity:
\[ \text{Molarity (M)} = \frac{0.1 \text{ N}}{2} = 0.05 \text{ M} \]

### Step 4: Calculate the Number of Moles
Now we can calculate the number of moles of oxalic acid needed using the formula:
\[ \text{Number of moles} = \text{Molarity} \times \text{Volume in L} \]
Substituting the values we have:
\[ \text{Number of moles} = 0.05 \text{ M} \times 0.25 \text{ L} = 0.0125 \text{ moles} \]

### Step 5: Calculate the Mass of Oxalic Acid
To find the mass of oxalic acid required, we use the formula:
\[ \text{Mass} = \text{Number of moles} \times \text{Molecular mass} \]
Given that the molecular mass of oxalic acid is 126 g/mol:
\[ \text{Mass} = 0.0125 \text{ moles} \times 126 \text{ g/mol} = 1.575 \text{ g} \]

### Conclusion
The amount of oxalic acid required to prepare 250 mL of a 0.1 N solution is **1.575 grams**.

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