1. The problem statement, all variables and given/known data Graphite can be change into diamond according to the following equation: Cgraphite ==> Cdiamond Consider the following reaction equations: Cgraphite + O2 (g) ==> CO2 (g) ΔH = -393.5 kJ/mol Cdiamond + O2 (g) ==> CO2 (g) ΔH = -393.4 kJ/mol Which form of carbon - graphite or carbon - is considered the standard state of carbon? 2. The attempt at a solution I tried to use Hess' Law of Summation and determined that to go from graphite to diamond, it takes -0.1 kJ/mol. To go from diamond to graphite, it takes 0.1 kJ/mol. I don't know how I can use this information to determine the standard state.