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Molar enthalpy of reactions

  1. Mar 10, 2005 #1
    I'm having some trouble with getting the correct entahlpy for the rxn:

    NaOH + NH4Cl --> NaCl + NH3 + H2O

    I've gotten the net ionic to be:

    OH + NH4 --> NH3 +H2O

    individuals to be sum of products (-) sum of reactants:

    (-80.83+-285.84)-(-229.94 (for OH) and NH4 doesn't show anyvalue in my book.

    This comes out to -136.73 which according to the little answer checker I've got here, is wrong. Where am I amiss?

    Can anyone shed some light?
  2. jcsd
  3. Mar 10, 2005 #2


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    The NH4+ ion has a standard heat of formation of -132.5 kJ/mol. Assuming everything else is right, that should do it.
  4. Mar 10, 2005 #3


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    The net ionic equation should simply be the formation of water

    [tex]H^+_{(aq)} + OH^-_{(aq)} \xrightarrow ~H_2O_{(l)} [/tex]
    This should be around -55kJ/mol

    although it actually depends on the solubility of ammonium chloride, I may be wrong.
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