1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar

    Staff: Mentor

    Think in terms of the exo- and endothermic reaction. Where does the reaction heat come from?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook