If the enthalpy of combustion of diamond and graphite are `-395.4kJ mol^(-1)` and `-393.6 kJ mol^(-1)` what is the enthalpy change for the C (graphite) `rarr` C (diamond) conversion ?

Explanation

C(diamond) `+O_(2)(g) rarr CO_(2)(g) Delta = -395.4 kJ mol^(-1)`
C (graphite) `+ O_(2)(g) rarr CO_(2)(g)Delta H = -393.6 kJ mol^(-1)` …(2)
C (graphite) `rarr "C(diamond)"_(1)` substracting (1) from (2), we get
C (graphit) `rarr "C(diamond)" DeltaH = -393.6 kJ - (-395.4 kJ)`,
`Delta H = +1.8 kJ mol^(-1)`.