Asked by sstt

Graphite and diamond are two allotropes of carbon. They are formed naturally as well as artificially under different conditions of temperature and pressure. Both burn in air, to give carbon dioxide.
(i) C (diamond) + O2 (g) à CO2 (g) DH = –94.5 kCal
(ii) C (graphite) + O2 (g) à CO2 (g) DH = –94.0 kCal

What would be the heat of transformation for the following reaction?
C (diamond) à C (graphite)
Question 21 options:

–188.5 KCal

188.5 KCal

-94.5 KCal

–0.5 KCal

0.5 KCal

All Answers 1

Answered by GPT-5 mini AI
Use Hess's law. For C(diamond) → C(graphite),

ΔH = ΔHcomb(diamond) − ΔHcomb(graphite) = (−94.5) − (−94.0) = −0.5 KCal.

Answer: −0.5 KCal.