Equivalent weight of crystalline oxalic acid is

Options

A. 90
B. 63
C. 53
D. 45

Answer

To find the equivalent weight of crystalline oxalic acid, we will follow these steps:

### Step 1: Understand the Structure of Crystalline Oxalic Acid
Crystalline oxalic acid (C₂H₂O₄·2H₂O) consists of oxalic acid with two water molecules of crystallization. The formula for oxalic acid is C₂H₂O₄.

### Step 2: Determine the N Factor
The n factor of an acid is the number of protons (H⁺ ions) it can donate. Oxalic acid has two acidic hydrogen atoms, which means it can dissociate to release two protons. Therefore, the n factor for crystalline oxalic acid is 2.

### Step 3: Calculate the Molecular Weight
To find the molecular weight of crystalline oxalic acid, we need to sum the atomic weights of all the atoms in its formula:

- Carbon (C): There are 2 carbon atoms, and the atomic weight of carbon is 12 g/mol.
\[ 2 \times 12 = 24 \text{ g/mol} \]

- Hydrogen (H): There are 2 hydrogen atoms from oxalic acid and 4 from the water of crystallization (2H₂O), totaling 6 hydrogen atoms.
\[ 6 \times 1 = 6 \text{ g/mol} \]

- Oxygen (O): There are 4 oxygen atoms from oxalic acid and 2 from the water of crystallization, totaling 6 oxygen atoms.
\[ 6 \times 16 = 96 \text{ g/mol} \]

Now, add these together to get the total molecular weight:
\[ \text{Molecular Weight} = 24 + 6 + 96 = 126 \text{ g/mol} \]

### Step 4: Calculate the Equivalent Weight
The equivalent weight is calculated using the formula:
\[ \text{Equivalent Weight} = \frac{\text{Molecular Weight}}{\text{N Factor}} \]
Substituting the values we found:
\[ \text{Equivalent Weight} = \frac{126 \text{ g/mol}}{2} = 63 \text{ g/equiv} \]

### Conclusion
The equivalent weight of crystalline oxalic acid is 63 g/equiv.

### Final Answer
**Option B: 63**

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