At a particular temperature, K = 3.75 for the following reaction.

Question

SO2(g) + NO2(g) SO3(g) + NO(g)
If all four gases had initial concentrations of 0.870 M, calculate the equilibrium concentrations of the gases.

Answer 1

First you must determine Q in order to know which way the reaction will move.
Qrxn = (NO)(SO3)/(SO2)(NO2) = 1.00 so the reaction will move to the right.
............SO2 + NO2 ==> SO3 + NO
initial....0.870.0.870..0.870..0.870
change.....-x.....-x.....x.....x
equil.....0.870-x etc.

Substitute from the ICE chart above into K expression and solve for x, then evaluate the concns of each gas.