Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Acid test

  1. Feb 27, 2005 #1
    Got a question about the energy dissipated during the formation of hydrochloric acid, upon the reaction of hydrogen and chlorine (photochemical reaction). Whats the exothermic energy involved and the intensity of light needed to activate this reaction, in other words the activation energy. And what would be the enrgy required to seperate H2 and Cl2 from a solution of HCl by electrolytic process?
    thnx let me know soon.
  2. jcsd
  3. Feb 27, 2005 #2
    are you sure this is a physics question? I believe that this is more general chemistry.
    the endothermic and exothermic energies are all derived experimentally. this means they are not always the same. There are too many factors that affect it like pressure and temperature (eg. when it's 110*C out you need to add less heat than when it's -30 degrees out). You could try the CRC handbook to get these data. :)
  4. Feb 27, 2005 #3


    User Avatar
    Science Advisor
    Homework Helper

    You simply need to find the bond energies of [itex]Cl_2, H_2 [/itex]. Add these two up, I believe that it'll be the activation energy. What light energy corresponds to this energy; you should definitely know this.

    To find the exothermic energy, you'll need to incorporate the bond energy of HCl. Draw the process out. You've got diatomic gases, you dissociate them, then these species reassociate.

    The electrolytic aspect pertains to free energy. You can find the voltage values of each of the reactions I mentioned and work from there.
  5. Mar 1, 2005 #4
    thanx a lot im sure that will help
  6. Mar 1, 2005 #5


    User Avatar
    Science Advisor

    Last edited by a moderator: Apr 21, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook