Question

Consider the following reaction and associated equilibrium constant: aA(g)+bB(g)⇌cC(g), Kc = 5.0

a.) Find the equilibrium concentrations of A, B, and C for a=1, b=1, and c=2. Assume that the initial concentrations of A and B are each 1.0 M and that no product is present at the beginning of the reaction.

Express your answer using two significant figures. Enter your answers separated by commas.

b.) Find the equilibrium concentrations of A, B, and C for a=1, b=1, and c=1. Assume that the initial concentrations of A and B are each 1.0 M and that no product is present at the beginning of the reaction.

Answer 1

x= change due to equilibrium

[A] [B [C]

Initial 1 1 0

Equilibrium 1-x 1-x 2x

Equilbrium constant for A+B----> 2C ( a=1, b= 1 and c=2

K =[C] ²/ [A] [B] =5.

4x²/(1-x)²= 5

x^2/ (1-x)² =5/4 =1.25

taking square root both sides

x/(1-x)= 1.12

x= 1.12-1.12x 2.12x = 1.12 , x =1.12/2.12 =0.53

At Equilibrium [A] =[B] =1-0.53 =0.47 [C] =2*0.53= 1.06

b) for a= 1, b=1 and c=1

C will be x instead of 2x

Kc= x²/(1-x)²= 5

taking square root both side

x/(1-x) =2.24

x= 2.24- 2.24x

3.24x =2.24

x= 2.24/3.24 =0.69

At equilibium [A] =[B] = 1-0.69= 0.31 [C] =0.69

b) for a= 1 b= 1 and c=1 at equilibrium there will be 1x rather than 2x

x²/(1-x)²= 5.0