Calculate the enthalpy change accompanying the transformation of C(graphite) to C(diamond). Given that the enthalpies of combustion of graphite and diamond are 393.5 and 395.4 KJ respectively

Explanation

We are given (i) C (graphite) `+ O_(2)(g) rarr CO_(2)(g) , Delta _(c ) H^(@)= - 393.5 kJ mol^(-1)`
(ii) C (diamond) `+ O_(2)(g) rarr CO_(2)(g), Delta _(c ) H^(@) = - 395.4 kJ mol^(-1)`
We aim at C( graphite ) `rarr ` C ( diamond) `, Delta _("trans") H^(@) = ?`
Subtracting eqn. (ii) from eqn. (i), we get
or C(graphite)- C (diamond) `rarr 0 , Delta _(r) H^(@) = - 393.5 - ( - 395.4) = + 1.9 kJ`