What will be the enthalpy change of conversion of graphite into diamond

Explanation

To determine the enthalpy change of the conversion of graphite into diamond, we can follow these steps:

### Step 1: Understand the Reaction
The conversion of graphite (C) to diamond (C) can be represented as:
\[ \text{C (graphite)} \rightarrow \text{C (diamond)} \]

### Step 2: Identify the Stability of the Phases
Graphite is known to be more stable than diamond at room temperature and pressure. This is due to the lower enthalpy of formation of graphite compared to diamond.

### Step 3: Determine the Enthalpy Change
The enthalpy change (ΔH) for the conversion of graphite to diamond can be derived from standard enthalpy of formation values. The enthalpy of formation of graphite is defined as zero (0 kJ/mol) because it is the reference form of carbon. The enthalpy of formation for diamond is positive, indicating that it requires energy to form diamond from graphite.

### Step 4: Use Standard Enthalpy Values
From thermodynamic tables, we find:
- ΔH_f (diamond) = +1.9 kJ/mol (approximately)
- ΔH_f (graphite) = 0 kJ/mol

Thus, the enthalpy change for the conversion can be calculated as:
\[ \Delta H = \Delta H_f (\text{diamond}) - \Delta H_f (\text{graphite}) \]
\[ \Delta H = 1.9 \, \text{kJ/mol} - 0 \, \text{kJ/mol} \]
\[ \Delta H = +1.9 \, \text{kJ/mol} \]

### Step 5: Conclusion
The enthalpy change for the conversion of graphite into diamond is approximately +1.9 kJ/mol. This positive value indicates that the conversion is endothermic, meaning it requires energy input.

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