Given the following data:
2NH3(g) --> N2(g) + 3 H2(g) deltaH* = 92KJ
2H2(g) + O2(g) --> 2H20(g) deltaH* = -484KJ
Calculate deltaH for the reaction:
2N2(g) + 6H2O(g) --> 3O2(g) + 4NH3(g)
Lets number the reaction as 1, 2, 3 from top to bottom
required reaction should be written in terms of other
reaction
This is Hess Law
required reaction can be written as:
reaction 3 = -2 * (reaction 1) -3 * (reaction 2)
So, ΔHo rxn for required reaction will be:
ΔHo rxn = -2 * ΔHo rxn(reaction 1) -3 * ΔHo rxn(reaction 2)
= -2 * (92.0) -3 * (-484.0)
= 1268 KJ
Answer: 1268 KJ
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