In: Chemistry
1. If the G o ’ value for an isomerization reaction, A A’ is 2.7 kcal/mole at 37 C,
a) what is the ratio of A’ and A at equilibrium?
b) What is G’ for the reaction if A’ is reacted soon after it is formed and its concentration is reduced to 1/10 x the normal equilibrium concentration? The concentration of A doesn’t change and just consider the concentration effect on G’, not the linkage to a second reaction.
The box next to G is a delta symbol.
a)
delta G = 2.7 KCal/mol
= 2700 Cal/mol
= 2700*4.184 J/mol
= 11296.8 J/mol
equilibrium constant, Kc= [A'] / [A]
T = 37 oC = (273 + 37) K = 310 K
Use:
delta G = -R*T*ln Kc
11296.8 = -8.314* 310 * ln ( [A'] / [A])
ln ( [A'] / [A]) = -4.383
[A'] / [A] = 0.0125
Answer: 0.0125
b)
new Kc = [new A'] / [new A]
= 1/10 * [A'] / [A] since new A' = 1/10 *
A'
= 1/10 * old Kc
= 1/10* 0.0125
= 0.00125
delta G'= -R*T*ln Kc
= -8.314*310 * ln (0.00125)
= 17228.5 J/mol
= 17228.5 / 4.184 cal/mol
= 4117.7 cal/mol
= 4.12 KCal/mol
Answer: 4.12 KCal/mol