Question

2 mole of pcl5 were introduced in a vessel of 5 litre capacity of a particular of 5 litre capacity of a particular temperature at equilibrium of pcl5 was found to be 35% dissociate into pcl3 and cl2 the value of kc for the reaction is

Answer 1

Answer: The value of the equilibrium constant is 0.005

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios.

Initial moles of  $PCl_5$ = 2 mole

Volume of container = 5 L

Initial concentration of $PCL_5=\frac{moles}{volume}=\frac{2moles}{5L}=0.4M$

The given balanced equilibrium reaction is,

                  $PCL_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)$

Initial conc.            c            0     0

At eqm. conc.    $c-c\alpha$        $c\alpha$       $c\alpha$  

The expression for equilibrium constant for this reaction will be,

$K_c=\frac{[PCl_3]\times [Cl_2]}{[PCl_5]}$

Give c= 0.4 M and $\alpha$ = 0.35

Now put all the given values in this expression, we get :

$K_c=\frac{(0.4\times 0.35\times 0.4\times 0.35)}{0.4-0.4\times 0.35}$

$K_c=0.005$

Thus the value of the equilibrium constant is 0.005