Question

Question 7 Below what temperature does the following reaction become nonspontaneous? 12(s) + Cl2(g)--2 ICI(s) ΔΗ +36.0 kJ: ΔS +158.8 J/K O 227 K O This reaction is spontaneous at all temperatures. O 313 K O This reaction is nonspontaneous at all temperatures. O 128 K

Answer 1

ΔH = 36.0 KJ/mol

ΔS = 158.8 J/mol.K

= 0.1588 KJ/mol.K

use:

ΔG = ΔH - T*ΔS

for reaction to be non spontaneous, ΔG should be positive

that is ΔG>0

since ΔG = ΔH - T*ΔS

so, ΔH - T*ΔS > 0

36.0- T *0.1588 > 0

T * 0.1588 < 36.0

T < 227 K

Answer: 227 K