Question

1) Initially, only H2S is present at a pressure of 0.244 atm in a closed container. What is the total pressure in the container at equilibrium? At a certain temperature, the Kp for the decomposition of H2S is 0.763. H2S- H2+S

2)If a 2.40 M sample of A is heated to 500 K, what is the concentration of B at equilibrium?

A(aq)-2B(aq) Kc=2.62*10^-6 at 500 K

Answer 1

1) The reaction is,

H2S ------> H2 + S

0.244 - p .....p.....p ...... (At equilibrium)

Kp = p * p / (0.244 - p)

=> 0.763 = p^2 / (0.244 - p)

Solving the abve equation, we get

p = 0.1944 atm

Total Pressure at equilibrium = (0.244 - p) + p + p = 0.244 + p = 0.438 atm

2) The reaction is,

A ------> 2B

2.4 - X....2X

Kc = [B]^2 / [A]

=> 2.62 x 10^-6 = (2X)^2 / (2.4 - X)

=> 2.62 x 10^-6 = 4X^2 / (2.4 - X)

Solving the above equation, we get

X = 1.254 x 10^-3 M

[B] at equilibrium = 2X = 2.51 x 10^-3 M