What is the equilibrium constant for the following reaction?

Question

C + O2 <---> CO2

[A...] [CO2]^2

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[C]^2 [O2]^2

[B......] [CO2]

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[C] [O2]

[C.....] [C] [O2]

------------

[CO2]

[D......] [C]^2 [O2]^2

-----------------

[CO2]^2

Answer 1

To find the equilibrium constant for a reaction you need to remember 3 simple rules:

1) only gases and aqueous solutions are used in an equilibrium constant expression so you need to know what states all of your reactants and products are in.

2)  the equilibrium constant, which is Keq is written as a proportion of products over reactants:

Keq = [products] / [reactants]

3) any coefficients in the balanced chemical equation become exponents in the expression for Keq.

Keeping these three things in mind:

1) Since you do not have the states of matter written, I will assume they are all either gases or aqueous and therefore will all appear in the Keq expression.

2) products over reactants means CO2 will be on top, and O2  and C will be on bottom

3) in the balanced equation, neither the C, O2 nor the CO2 have coefficients, therefore none will have exponents in the expression.

Your answer must be B.