Question

1. What will be the concentration of Cl2O after a mixture that contains [H2O] = 1.00 M and [Cl2O] = 1.00 M comes to equilibrium at 25oC?

H2O (g) + Cl2O (g)   ⇄   2HOCl (g) Kc=0.0900

2. Calculate the pressure of Br2 (g) at equilibrium, in a mixture of Cl2, Br2, and BrCl, if the initial pressure of Cl2 and Br2 was 1.0 atm.

Cl2 (g) + Br2 (g)  ⇄ 2BrCl (g) Kp = 4.7 x 10-2

Answer 1

1)

H2O + Cl2O <=> 2 HOCl

..1 M..... 1M........... 0...............(initial) . . .. . . . . . .. . .

-x .. . - x.. . . . .+2x............... (change)

1 - x..... 1 - x ...... 2x............ (equilibrium)

Kc = [HOCl] ^2 / [H2O] [Cl2O]

0.090 = (2x)^2 / (1 - x) ^2

Taking square root both the sides

0.3 = 2x/ (1 - x )

0.3 - 0.3 x = 2x

2.3 x = 0.3

x = 0.130 M

So, Cl2O equilibrium concentration = 1 - x

= (1 - 0.130) M

= 0.87 M

2)

Cl2 + Br2 <=> 2 BrCl

..1 atm... 1 atm......... 0...............(initial) . . .. . . . . . .. . .

-x .. . - x.. . . . .+2x............... (change)

1 - x.. ... 1 - x ...... 2x............ (equilibrium)

Kp = pressure of (BrCl) ^2 / pressure of (Br2) x pressure of (Cl2)

4.7 x 10^-2 = (2x)^2 / (1 - x) ^2

Taking square root both the sides

0.216 = 2x/ (1 - x )

0.216 - 0.216 x = 2x

2.216 x = 0.216

x = 0.097 M

So, Br equilibrium pressure = 1 - x

= (1 - 0.097)

= 0.903