How can we find #DeltaH_"rxn"^@# for...? #NaOH(s) + HCl(g) rarr NaCl(s) + H_2O(l)#?

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Answer 1 · 2017-04-09T16:51:57

You normally would quote INDIVIDUAL #DeltaH_f^@# for reactants and products.

I get #DeltaH_"rxn"^@=-134.7*kJ*mol^-1.#

But, we can find #DeltaH_f^@# for the participating species on the interwebz..... :

#NaOH(s) + HCl(g) rarr NaCl(s) + H_2O(g)#

And the various #DeltaH_f^@# are taken from the given site.

#NaOH(s),# #DeltaH_f^@=-426.0*kJ*mol^-1#

#NaCl(s),# #DeltaH_f^@=-411.2*kJ*mol^-1#

#HCl(g),# #DeltaH_f^@=-92.3*kJ*mol^-1#

#H_2O(g),# #DeltaH_f^@=-241.8*kJ*mol^-1#

Now #DeltaH_"rxn"^@=SigmaDeltaH_f^@"products"-SigmaDeltaH_f^@"reactants"#

#{(-241.8-411.2)-(-426.0-92.3)}*kJ*mol^-1=-134.7*kJ*mol^-1#

If I were you, I would check on the #DeltaH_f^@# values. All care taken, but no responsibility admitted.......