Question

Predict whether the following reactions will be exothermic or endothermic

A.] N2 (g) + 3H2 (g) --> 2NH3 (g)
B.] S (g) + O2 (g) --> SO2 (g)
C.] 2 H2O (g) --> 2 H2 (g) + O2 (g)
D.] 2 F (g) --> F2 (g)

Bond ________ ∆H˚ (kJ/mol)
H-H _________ 432
N(triple)N ____942
O=O ________494
F-F __________155
H-N _________ 386
H-O _________459
S=O _________ 522


Please help! I have no idea how to determine if a reaction is endothermic or exothermic!

Answer 1

delta Hrxn = (DHreactants)-(DHproducts)
If DHrxn is + it is endothermic.
If DHrxn is - it is exothermic.