Question

${\Delta }_{f}H$ of graphite is 0.23 kJ/mol and ${\Delta }_{f}H$ of diamond is 1.896 kJ/mol. $\Delta H_{transition}$ from graphite to diamond is :

• A. 1.66 kJ/mol
• B. 2.1 kJ/mol
• C. 2.33 kJ/mol
• D. 1.5 kJ/mol

Answer 1

Answer: (A)

1.66 kJ/mol

The enthalpy change for the transition is equal to the difference in the enthalpy change for the formation of diamond and the enthalpy change for the formation of graphite.

$\Delta H_{reaction}={\Delta }_f{H}_{\left(diamond\right)}-{\Delta }_f{H}_{\left(graphite\right)}$
$=1.896-0.23=1.666kJ/mol$