Question

Find the deltaG^o for the reaction using the following information:

6 C (s) + 3 H2 (g) ----> C6H6 (l)

2 C6H6 (l) + 15 O2 (g) ---> 12 CO2 (g) + 6 H2O (l) DeltaG^o= -6455 kJ

C(s) + O2 (g) ---> CO2 (g) DeltaG^o= -487 kJ

H2 (g) + 1/2 O2 (g) ---> H2O (l) DeltaG^o= -257 kJ  

Answer 1

Lets number the reaction as 0, 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 0 = -0.5 * (reaction 1) +6 * (reaction 2) +3 * (reaction 3)

So, deltaGo rxn for required reaction will be:

deltaGo rxn = -0.5 * deltaGo rxn(reaction 1) +6 * deltaGo rxn(reaction 2) +3 * deltaGo rxn(reaction 3)

= -0.5 * (-6455.0) +6 * (-487.0) +3 * (-257.0)

= -465.5 KJ

Answer: -465.5 KJ