For the change, `C_("diamond") to C_("graphite"), DeltaH = -1.89 kJ`, if 6g of diamond and 6g of graphite are separately burnt to yield `CO_2`, the heat liberated in first case is

Options

A. Less than in the second case by 1.89 kJ
B. Less than in the second case by 11.34 kJ
C. Less than in second case by 14.34 kJ
D. More than in the second case by 0.945 kJ

Answer

To solve the problem, we need to calculate the heat liberated when 6 g of diamond is burnt to yield CO2. We know that the enthalpy change (ΔH) for the conversion of diamond to graphite is -1.89 kJ for 12 g of carbon (in this case, diamond).

### Step-by-Step Solution:

1. **Identify the given data**:
- ΔH for the conversion of diamond to graphite = -1.89 kJ for 12 g of diamond.
- We need to find the heat liberated when 6 g of diamond is burnt.

2. **Calculate the heat change for 6 g of diamond**:
- Since the enthalpy change of -1.89 kJ corresponds to 12 g of diamond, we can find the heat change for 6 g by using a proportion.
- Heat change for 6 g of diamond = (ΔH for 12 g) × (6 g / 12 g)
- Heat change for 6 g of diamond = -1.89 kJ × (1/2) = -0.945 kJ

3. **Interpret the result**:
- The negative sign indicates that heat is released during the combustion of diamond. Therefore, the heat liberated when 6 g of diamond is burnt is 0.945 kJ.

### Final Answer:
The heat liberated when 6 g of diamond is burnt to yield CO2 is **0.945 kJ**.

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