2 SO2(g) + O2(g) <==> 2SO3(g)
Initially, 1.6mol SO3 is placed in a 3.0L container. At equilibrium, [O2] = 0.15M. What is the value of Keq?
A. 0.26
B. 1.2
C. 4.0
D. 43
My work:
...2SO2...+...O2...<==>...2SO3
I 0.53M.....-----.........-----
C +0.15.....+0.15........-0.15
E 0.53+0.15..0.15........-0.15
Keq = (-0.15)^2/(0.53+0.15)^2(0.15)= .321M
what am I doing wrong?
oh I realized, I have my 0.53M on 2SO2 and not 2SO3.
Keq = (0.53-0.30)^2/(0.30)^2(0.15) = 0.26
Is this correct? :)
Looks like the second set up is correct but you punched in the wrong numbers on your calculator. I get about 4 or close to that.
I get 3.918... so does that mean I round up to 4.0? so the answer would be C?
Yes and no.
3.9 is the correct answer and I would not round up to 4 since you are allowed two s.f. in the answer. But you choose 4.0 as the answer since that's the closest of the choices.
To calculate the value of Keq, you need to use the concentrations of the substances at equilibrium. You correctly identified the changes in concentrations (C) for the equilibrium reaction, but you made a mistake in calculating the equilibrium concentrations (E).
Initially, you have 1.6 mol of SO3 in a 3.0 L container. Therefore, the initial concentration of SO3 is given by:
[SO3]initial = moles/volume = 1.6 mol / 3.0 L = 0.53 M
Assuming that the reaction reaches equilibrium, you are told that the concentration of O2 at equilibrium is [O2] = 0.15 M. However, you didn't mention the concentration of SO2 at equilibrium.
To find the equilibrium concentration of SO2, you need to use the stoichiometry of the balanced equation. According to the equation, 2 moles of SO2 react with 1 mole of O2 to produce 2 moles of SO3. So, the concentration of SO2 is twice the concentration of O2 at equilibrium. Therefore:
[SO2] = 2 * [O2] = 2 * 0.15 M = 0.30 M
Now, you have the equilibrium concentrations:
[SO2] = 0.30 M
[O2] = 0.15 M
[SO3] = 0.53 M
Now, you can correctly calculate the value of Keq:
Keq = ([SO3]^2) / ([SO2]^2 * [O2])
= (0.53^2) / (0.30^2 * 0.15)
≈ 4.0
Therefore, the correct answer is option C.