Achieve Week 1, HW #2

[bernal_maria1A]

Hi! I'm having trouble solving question 2 on the Achieve HW.
At a certain temperature, 0.760 mol SO3 is placed in a 3.50 L container. At equilibrium, 0.160 mol O2 is present. Calculate Kc. I'm making an ICE table but still have no luck! Any help would be much appreciated!

[Kayley Steele 3D]

First you must convert mol to M and then make your ICE box. You should get" M of SO3" -2x, 0+2X SO2 and X O2 for the equilibrium values. Since we were told the moles of O2 at equilibrium we know that x equals this value, 0.160. You can then use the Kc formula to solve for the Kc from here.

[LavieTran2B]

Hi,

Your initial moles for SO3 will be 0.760. Since it gives you the 0.160 mol of O2 at equilibrium this will be in the column under O2 for the "E" part of the ice table. Your ICE table should look like this:

2SO3 --> 2SO2 + O2
<--
I 0.760 0 0
C -2x +2x x
E 0.760 - 2x 0.760 - x 0.160

Don't forget to convert to molarity!

[Aparna Pillai 1E]

Hi! Make sure you have an initial amount for SO3, as given in the problem, and no initial amount for either of the products. You can use moles or molar concentration for your ICE table. Since you know the equilibrium amount for O2, you can calculate the change and therefore the relative changes for SO3 and SO2 as well (depending on the coefficients). That will help you obtain final equilibrium concentrations for each species, which you can then use to calculate Kc.

[Abigail Tran 14a]

find concentration of acid then divide it by the concentration given in the question and multiply by 100 to get perventage