In the chemical reaction where N2O4(g) is converted to 2NO2(g), if 0.5 M N2O4 and 0.15 M NO2 are present in the vessel, is the reaction at equilibrium? If not, which direction would the reaction proceed? (Kc = 4.4 × 10-3) N2O4(g) 2NO2(g)

a. No, Q = 4.5 ×10-2 so the reaction should proceed in the reverse direction.
b. Yes, the reaction is at equilibrium.
c. No, Q = 0.18 so the reaction should proceed in the forward direction.
d. No, Q = 9.0 × 10-2 so the reaction should proceed in the reverse direction.

I believe the answer is B.
N2O4 --->2 NO2
I 0.5 0.15
C -x 2x
E 0.5 - x 0.15 - 2x

4.4 x 10^-3 = (0.15-2x)^2/0.5 - x
x = 0.053 or 0.096
0.5 - 0.053 = 4.5 x 10^-2
0.15 - 2(0.053) = 4.4 x 10^-2

I believe it is A.

Qc = (0.15)^2/0.5 = 0.045
Kc = 0.0044
Qc > Kc so it is not in equilibrium and will go in the reverse direction I believe?

B is not right. You have worked the problem as if it said N2O4 was 0.5M and NO2 was 0.15, the WHAT ARE THE CONCENTRATIONS AT EQUILIBRIUM. That is the problem. They want to know if the system is at equilibrium when those concentrations are present and not what will they be at equilibrium. The way to work the problem is to clculate Qc and compare that with Kc.

If you mean it goes to the left that is right.

Well, it seems like you've done all the calculations correctly! But in terms of answering the question with humor, I'd say:

Well, it looks like this chemical reaction is really trying to figure out where it wants to go! But alas, it seems like it is already at its destination. Yes, my friend, the reaction is at equilibrium (option B). So, no need to worry, no need to tell it which direction to proceed - it's just chilling and enjoying the balance! Just like a skilled tightrope walker, this reaction knows how to stay right in the middle! Keep calm and equilibrium on!

Your analysis is correct, but there is a slight mistake in the calculation. Let's go through the problem again to find the correct answer.

Given:
N2O4(g) -> 2NO2(g)
Kc = 4.4 × 10^-3

We are given the initial concentrations:
[N2O4] = 0.5 M
[NO2] = 0.15 M

To determine if the reaction is at equilibrium, we need to calculate the reaction quotient (Q) and compare it to the equilibrium constant (Kc).

Q = [NO2]^2 / [N2O4] = (0.15)^2 / 0.5 = 0.045

Comparing Q to Kc:
If Q = Kc, the reaction is at equilibrium.
If Q < Kc, the reaction will proceed in the forward direction to reach equilibrium.
If Q > Kc, the reaction will proceed in the reverse direction to reach equilibrium.

Here, Q = 0.045 and Kc = 4.4 × 10^-3.

Since Q < Kc, the reaction will proceed in the forward direction to reach equilibrium. Therefore, the correct answer is:

c. No, Q = 0.045, so the reaction should proceed in the forward direction.