For each of the following reactions, calculate ? H ?rxn, ? S ?rxn, ? G ?rxn at 2
ID: 1046474 • Letter: F
Question
For each of the following reactions, calculate ?H?rxn, ?S?rxn, ?G?rxn at 25 ?C. State whether or not the reaction is spontaneous. If the reaction is not spontaneous, would a change in temperature make it spontaneous? If so, should the temperature be raised or lowered from 25 ?C?
Part A
2CH4(g)?C2H6(g)+H2(g)
?H?rxn=
?S?rxn=
?G?rxn=
Is this reaction spontaneous?
Part B
2NH3(g)?N2H4(g)+H2(g)
?H?rxn=
?S?rxn=
?G?rxn=
Is this reaction spontaneous?
Part C
N2(g)+O2(g)?2NO(g)
?H?rxn=
?S?rxn=
?G?rxn=
Is this reaction spontaneous?
Explanation / Answer
2CH4(g)?C2H6(g)+H2(g)
?H?rxn= ?H0f products - ?H0f reactants
= (0 -84.68) -(2*-74.85) = 65.02KJ
?S?rxn=S0f products - S0f reactants
= (130.58 +229) -(2*186.27) = -12.96J/mole-K
?G?rxn=?H?-T?S0
= 65.02 -298*-0.01296 = 68.88KJ/mole
?G?rxn>o it is non spontaneous reaction.
Part B
2NH3(g)?N2H4(g)+H2(g)
?H?rxn=?H?f products - ?H?f reactants
= (0 +95.39) -(2*-46.1) = 187.59KJ/mole
?S?rxn= S0 f products - S0f reactans
= 130.58 +121.2 -(2*192.34) = -132.9J/mole-K
?G?rxn=?H?-T?S0
= 187.59 -298*-0.1329 = 227.2KJ/mole
?G?rxn>o it is non spontaneous reaction.
N2(g)+O2(g)?2NO(g)
?H?rxn= ?H?rxn= ?H0f products - ?H0f reactants
= 2*90.25 - (0 +0) = 180.5KJ/mole
?S?rxn=S0f products - S0f reactants
= 2*210.65- (191.5 +205) = 24.8J/mole-K
?G?rxn=?H?-T?S0
= 180.5 -298*-0.0248 = 187.9KJ/mol
?G?rxn<o it is spontaneous reaction.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.