Question #bcedf

1 Answer
Jun 5, 2015

The problem can be solved by Gibb's free energy equation.

Gibbs free energy ( #G#), gives us the enthalpy change of a reaction, #DeltaH#, minus the entropy change of the reaction system, #DeltaS_(sys)#, multiplied by the temperature of the reaction, #T#.
#DeltaG=DeltaH−TDeltaS_(sys)# (Review concept )

A positive Gibb's free energy change (#DeltaG#) signifies a non- spontaneous change while a negative change signifies a spontaneous one. A zero change indicates a state of chemical equilibrium at the given temperature.

To determine the threshold temperature at which a transition from spontaneous to non-spontaneous change happens, we need to determine the temperature for which #DeltaG = 0#

Substituting values,

#-1036 * 10^3J - T (K)*-153.2 JK^(-1)= 0#
#=>153.2*T = 1036*10^3#
#=>T = 6762.40 K #

So, above #6762.4 K# the reaction becomes non-spontaneous.