Consider a reaction where S rxn = -315 J/K and H rxn = -45.6 kJ. Which statement
ID: 959104 • Letter: C
Question
Consider a reaction where S rxn = -315 J/K and H rxn = -45.6 kJ. Which statement is true about the spontaneity of this reaction?
a. This reaction is nonspontaneous at 25°C but will become spontaneous if the temperature is increased to 145°C.
b.This reaction is spontaneous at 25°C, but will become nonspontaneous if the temperature is decreased to -130°C.
c.This reaction is nonspontaneous at 25°C but will become spontaneous if the temperature is decreased to -130°C.
d.Decreasing the temperature will have no effect on the spontaneity of the reaction. It is nonspontaneous at 25°C and will become even less spontaneous as the temperature decreases.
Explanation / Answer
answer : This reaction is nonspontaneous at 25°C but will become spontaneous if the temperature is decreased to -130°C
S rxn = -315 J/K = - 0.315 kJ/K
H rxn = -45.6 kJ.
G = H - T x S
if the reaction is to be spontenous, G should be less than zero. or negative .
G < 0
0 < H - T x S
H < T x S
- 45.6 < T x - 0.315
145 K < T
- 128oC < T