11.59

[Skolli20]

Hi everyone, so while I was doing the chapter 11 homework, I came across this problem - A reaction mixture is prepared by mixing 0.100 mol SO2, 0.200 mol NO2, 0.100 mol NO, and 0.150 mol SO3 in a 5.00-L reaction vessel. The reaction SO2(g) NO2(g) ∆ NO(g) SO3(g) is allowed to reach equilibrium at 460 C, when Kc 85.0. What is the equilibrium concentration of each substance?


In the answer key, it said to calculate Q after getting the initial concentrations and then proceed with ICE... I was wondering why we had to calculate Q first? Why can't we just do ICE? In other words, why do we need to know that the reaction will proceed to proceed to produce more products cuz Q < K?

[vsyacoubian2A]

You need to calculate Q in order to know which way the reaction will go in order to reach equilibrium. That way, when you are setting up your ice box, you will know whether to put + or - x for reactants and products for the change (c).