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Homework Help: Determining Standard State

  1. Jan 30, 2014 #1
    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.
  2. jcsd
  3. Jan 30, 2014 #2


    User Avatar

    Staff: Mentor

    The one with lower energy content is the more stable one.
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