Answer to Question #128980 in General Chemistry for A

Question

Good day,

For a different reaction, Kc= 7.45×106, kf=6.05×104s−1 and kr=8.12×10−3 s−1
. Adding a catalyst increases the forward rate constant to 2.93×107 s−1
. What is the new value of the reverse reaction constant, after adding catalyst?
I think the answer is 1.28x10^13 but unsure if the units,please help.
Thanks

Answer 1

A catalyst accelerates both forward and reverse reactions, but doesn't affect the equilibrium. So kf and kr change while Kc remains constant.

From a relation between constants Kc=kf/kr:

Kr=kf/Kc,

Kr_cat=kf_cat/Kc=2.93×10^7s^-1/7.45×10^6=3.93 s^-1.

The units of the constant of reverse reaction is the same as of the constant of the forward reaction, while equilibrium constant is unitless.