Had a chemistry worksheet and am stuck on these last few problems. Please help w
ID: 633652 • Letter: H
Question
Had a chemistry worksheet and am stuck on these last few problems. Please help with any you can help with. Will rate!!
a) Why can a change be spontaneous even though the system entropy decreases? Identify a spontaneous change in which the entropy of the system decreases.
b) The heat of vaporization of 1.0 mole of water at 100 degrees celcius and 1.0 atm is 40.6 kJ. Calculate the change in entropy for the process H20(l)-->H20(g).
c) Calculate the free energy change for the following reaction and predict whether the reaction occurs spontaneously at 25 degrees celcius. H2(g)+CO2(g)-->H20(g)+CO(g); ?H=41.8 kJ, ?S=42.1 J/K
Explanation / Answer
SORRY FOR WRONG ANS PREVIOUSLY
HERE IS THE CORRECT SOLUTION
Original equation:-
H2(g)+CO2(g)-->H20(g)+CO(g)
Enthalpies of formation at 298K from data book:-
?H (CO2) = -393.509 Kj/mol
?H (H2) =0
?H (H2O) = -241.818 Kj/mol
?H (CO) = ?110.525 Kj/mol
??H = -241.818 -110.525 - (-0 -393.509)
??H = -41.166 kj/mol
Entropy values at 298K from data book:-
?S(CO2) = 0.2137 kj/mol-k
?S(H2) = 0.1307 kj/mol-k
?S(H2O) = 0.1888 kj/mol-k
?S(CO) = 0.1977 kj/mol-k
??S= 0.2137+0.1307 - (0.1888+0.1977)
??S= -0.0421 kj/mol-k
Now ?G = ?H - T?S
?G = -41.166 - 298x (-0.0421)
?G = -28.6202 kj/mol
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