Applying Hess\'s Law calculate the delta H for the reaction: 5C(s) + 6H2(g) = C5

Question

Applying Hess's Law calculate the delta H for the reaction: 5C(s) + 6H2(g) = C5H12(l). Use the following 3 reactions:
1. C5H12(l) + 8O2(g) = 5CO2(g) + 6H2O(l) delta H = -3505.8 kj
2. C(s) + O2(g) = CO2(g) delta H= -393.5 kj
3. 2H2(g) + O2(g) = 2H2O(g) delta H = -483.5 kj

Please show work and give full explanation for calcuations

Explanation / Answer

flip first reaction multiply second reaction by 5 multiply third reaction by 3 the result: 5CO2(g)+6H2O(g) ---> C5H12(l)+8O2(g), Delta H= +3505.8 kJ 5C(s)+5O2(g)--------->5CO2(g), Delta H= -1967.5 kJ 6H2(g)+3O2(g)------->6H2O(g), Delta H= -1450.5 kJ Add the three revised reactions and cancel out like items (6H2O, 8O2, 5CO2). Add the three enthalpies and you have your answer.

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