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Homework Help: Which one has the higher enthalpy, the reactent or the product?

  1. Jan 30, 2013 #1
    2Cl(g)→Cl2(g) ΔH = -243.4 KJ

    Which has the higher enthalpy under these conditions, 2 Cl (g) or Cl2 (g)?

    At first, I thought they would have the same change in enthalpy, because if I make it a reverse reaction, their magnitude will be the same. Then I realized that the signs would reverse, making the change of enthalpy for the product positive. Apparently that was not the answer, as 2 Cl(g) has a higher change in enthalpy. I'm posting this because I want to know why that is?
  2. jcsd
  3. Jan 31, 2013 #2


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    Staff: Mentor

    Think in terms of the exo- and endothermic reaction. Where does the reaction heat come from?
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