For the equilibrium pcl5(g) pcl3(g) + cl2(g), kc = 4.0 at 228°c. if pure pcl5 is placed in a 1.00-l container and allowed to come to equilibrium, and the equilibrium concentration of pcl5(g) is 0.26 m, what is the equilibrium concentration of pcl3?

Answer : The equilibrium concentration of is, 1.0 M

Explanation : Given,

Equilibrium concentration of = 0.26 M

Volume of solution = 1.00 L

Equilibrium constant = 4.0

The balanced equilibrium reaction will be,

The expression of equilibrium constant for the reaction will be:

From the reaction we conclude that the concentration of and are equal.

Let the concentration of be 'X'.

So, concentration of = X

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

Thus,

The concentration of at equilibrium = X = 1.0 M

The concentration of at equilibrium = X = 1.0 M

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.