Equilibrium - Result Question 12

####13. The value of equilibrium constant of the reaction

HI(g)12H2(g)+12I2 is 8.0

[2008]

The equilibrium constant of the reaction H2(g)+I2(g)2HI(g) will be:

(a) 116

(b) 164

(c) 16

(d) 18

Show Answer

Solution:

  1. (b) Given : Equilibrium constant (K1) for the reaction:

HI(g)K112H2(g)+12I2(g);K1=8;

To find equilibrium constant for the following reaction:

H2(g)+I2(g)2HI(g);K2=?

multiply (i) by 2 , we get

2HI(g)H2(g)+I2(g);

(iii)K1=82=64.

Now reverse equation (iii), we get

H2(g)+I2(g)2HI(g);K=164

Equation (iv) is the same as the required equation

(ii), thus K2 for equation (ii) is 164 i.e. option (b) is correct.

When the equation for an equilibrium is multiplied by a factor, the equilibrium constant must be raised to the power equal to the factor.

For a reversible reaction, the equilibrium constant of the backward reaction is inverse of the equilibrium constant for the forward reaction.



NCERT Chapter Video Solution

Dual Pane