Question

Question 3 1 pts Predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous. A. AS rxn= +100 J/K; AH rxn= +150 kJ [ Select] B. AS rxn= - 100 J/K; AH rxn= +200 kJ [Select]

Answer 1

3)

A)

ΔHrxn = 150.0 KJ

ΔSrxn = 100 J/K

= 0.1 KJ/K

use:

ΔGrxn = ΔHrxn - T*ΔSrxn

for reaction to be spontaneous, ΔGrxn should be negative

that is ΔGrxn<0

since ΔGrxn = ΔHrxn - T*ΔSrxn

so, ΔHrxn - T*ΔSrxn < 0

150.0- T *0.1 < 0

T *0.1 > 150.0

T > 1500 K

Answer: high temperatures

B)

ΔHrxn = 200.0 KJ

ΔSrxn = -100 JK

= -0.1 KJ/K

use:

ΔGrxn = ΔHrxn - T*ΔSrxn

for reaction to be spontaneous, ΔGrxn should be negative

that is ΔGrxn<0

since ΔGrxn = ΔHrxn - T*ΔSrxn

so, ΔHrxn - T*ΔSrxn < 0

200.0- T *-0.1 < 0

T *0.1 < -200.0

T < -2000 K

Since kelvin temperature can't be negative

The reaction will never be spontaneous

Answer: NO TEMPERATURES