Question

Given the concentrations, calculate the equilibrium constant for this reaction: PCl3(g) +Cl2(g)⇌PCl5(g) At equilibrium, the molar concentrations for reactants and products are found to be [PCl3]=0.20 M, [Cl2]=0.25 M, and [PCl5]=1.20 M. What is the equilibrium constant (Kc) for this reaction? Express your answer using two significant figures.

Answer 1

Answer: Thus the value of the equilibrium constant is $2.4\times 10^1$

Explanation:

Equilibrium constant is the ratio of the concentration of products to the concentration of reactants each term raised to its stochiometric coefficients.

 $PCl_3(g)+Cl_2(g)\rightleftharpoons PCl_5(g)$

At eqm. conc.    (0.20) M    (0.25) M      (1.20) M

The expression for equilibrium constant for this reaction will be,

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

$K_c=\frac{1.20}{0.20\times 0.25}=24=2.4\times 10^1$

The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.

Thus the value of the equilibrium constant is $2.4\times 10^1$