ThermochemistryHard

Question

The enthalpy of atomization of graphite is 698.6 kJ/mol and the mean bond enthalpy of C−C bond in diamond is 348.4 kJ/mol. The enthalpy of conversion of graphite into diamond is

Options

A.+1.2 kJ/mol
B.+1.8 kJ/mol
C.−1.2 kJ/mol
D.−1.8 kJ/mol

Solution

$C\left( \text{Graphite} \right) \rightarrow C\left( \text{Diamond} \right)$

$\Delta H = 698.6 - 2x348.4 = 1.8\text{ kJ/mol}$

(In diamond, there is 2C – C bonds per C – atom)

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