Define and explain the law of chemical equilibrium.

Asked by Topperlearning User | 16th Jun, 2016, 05:17: PM

Expert Answer:

The law of  chemicalequilibrium states that in a reversible reaction the ratio of the rate of the forward reaction to the rate of the reverse reaction is a      constant for that reaction at a constant temperatuere.
 
For a general chemical reaction
a A + b B rightwards harpoon over leftwards harpoon c C + d D
 
According to the law of mass action : rf =kf [A]a [B]b  and rb = kb[C]c [D]
At equilibrium point , rf =  rb
Or,kf [A]a [B]b  = kb[C]c [D]d      Or, kf/ kb = KC
KC =
[C]c [D]d

[A]a [B]b
 
Where Kc is the equilibrium constant and the notation [A] signifies the molar concentration of species A. An alternative expression for the equilibrium constant for reaction involving gaseous substances ( concentration expressed in partial pressure) is as below
KP =
PCc PDd

PAa PBb

Answered by  | 16th Jun, 2016, 07:17: PM