when to place equilibrium constant in front concentration for Kc expression?

Smooth Operater

don't bug "operatEr"!
10+ Year Member
5+ Year Member
May 22, 2004
for rxn C(s) + CO(g) --> 2 CO(g), what is the concentration of CO at equilibirum if the CO2 concentration is 0.5 M?

I am kinda confused about writing expression for equilibrium constant. How come in some questions, I need to place the stiochimetric coefficient in front the concentration like:

Kc = 2[CO]^2/[CO2]

and there are times that I don't need to place the coefficient to solve a problem correctly (such as this question) like:

Kc = [CO]^2/[CO2]

How some experts can clear it up. THANKS!


Med School 4.0
10+ Year Member
Nov 16, 2004
the Pale Blue Dot
Attending Physician
i've always raised the concentration of reactants and products to the power of their respective stoichiometric ratios.
About the Ads