Given N_2(g) +3H_2(g) rarr 2NH_3(g)+92*kJ...what energy is associated with the formation of A. "4 moles of ammonia"; and B. "4 g ammonia is produced"?

1 Answer
anor277
Oct 11, 2016

N_2(g) + 3H_2(g) rarr 2NH_3(g) + Delta

A. = -368*kJ; B. = -10.8*kJ

Explanation:

The given thermodynamic paramters are always quoted per mol of reaction as written. Thus if the one mole of dinitrogen reacts, -92*kJ*mol^-1 (of given reaction) are evolved. If 4 moles, then -368*kJ

If 4*g ammonia are produced, this is a molar quantity of (4.00*g)/(17.03*g*mol^-1) = 0.235*mol.

Given that -46*kJ are produced per mole of ammonia, this gives a quantity of -46*kJ*mol^-1xx0.235*mol = -10.8*kJ.

Why is this an important reaction?

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