When 1 g of anhydrous oxalic acid is burnt at `25^(@)C`, the amount of heat liberated is `2.835 kJ`.`Delta H` combustion is (oxalic acid : `C_(2)H_(2)O_(4))`

Options

A. `-255.15 kJ`
B. `-445.65 kJ`
C. `-295.24 kJ`
D. `-155.16 kJ`

Answer

To find the enthalpy change of combustion (ΔH_combustion) for oxalic acid (C₂H₂O₄), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Mass of oxalic acid burned (m) = 1 g
- Heat liberated (q) = 2.835 kJ

2. **Calculate the Molar Mass of Oxalic Acid (C₂H₂O₄):**
- Carbon (C): 12 g/mol × 2 = 24 g/mol
- Hydrogen (H): 1 g/mol × 2 = 2 g/mol
- Oxygen (O): 16 g/mol × 4 = 64 g/mol
- Total molar mass = 24 + 2 + 64 = 90 g/mol

3. **Determine the Heat Released for 90 g of Oxalic Acid:**
- Since the heat liberated for 1 g of oxalic acid is 2.835 kJ, we can calculate the heat for 90 g:
\[ \text{Heat for 90 g} = \text{Heat for 1 g} \times \frac{90 \text{ g}}{1 \text{ g}} = 2.835 \text{ kJ} \times 90 = 255.15 \text{ kJ} \]

4. **Account for the Sign of ΔH:**
- The combustion process releases heat, so we denote this as a negative value:
\[ \Delta H_{\text{combustion}} = -255.15 \text{ kJ} \]

5. **Final Answer:**
- The enthalpy change of combustion of oxalic acid is:
\[ \Delta H_{\text{combustion}} = -255.15 \text{ kJ/mol} \]