Question

At some temperature, the reaction

PCl3(g)+Cl2(g)====PCl5(g)

is at equilibrium when the concentration of PCl3, Cl2, and PCl5 are 10, 9.0, and 12 mol/L,
respectively. Calculate the value of Kc for this reaction at that temperature.

Answer 1

It is given that the reaction at the given temperature is in equilibrium.
Next check if the reaction is homogeneous: all gases, so homogeneous.
Now denote the stoichiometric coefficients by a,b and c for the reactants and products respectively (all equal to 1 in this case).
then Kc is given by:
Kc=[PCl5]^c/([PCl3]^a [Cl2]^b)
[] means concentration (mol/L).

Answer 2

Note that the coefficients in this equation are a, b, and c, and those have a value of 1 in this instance.

Answer 3

thanks =)