Dinitrogentetraoxide partially decomposes according to the following equilibrium:

N2O4 (g) -> 2NO2 (g)
<-

A 1.00-L flask is charged with 0.400 mol of N2O4. At equilibrium at 373 K, 0.0055 mol ofN2O4
remains. Keq for this reaction is ?.

hOw can i set up this problem?

Set up an ICE chart, substitute into the Keq expression, and solve for Keq. You want to convert moles to M (but that's easy since it's a 1 L flask.)

initial:
N2O4 = 0.400 M
NO2 = 0

change:
NO2 = +2x
N2O4 = -x

equilibrium:
NO2 = 2x
N2O4 = 0.400-x and the problem tells you this is 0.0055

Now do a little reasoning. Solve 0.400-x=0.0055 for x.
Multiply that by 2 to find NO2 at equilibrium.
Then substitute into Keq expression and solve for Keq.
Check my work.
0

whats the keq expression??'

sorry we're learning about ice charts tomorrow but the teacher gave us a practice worksheet for the coming quiz and i wanted to see if i could figure out some of the problems early.

i did everything you said and got

0.789 im at the step of setting up the keq expression

sorry to have gotten into this post, im solving a similar question and wanted to know how to do the final step

Your 0.789 is 2x and that is (NO2).

(N2O4) = 0.0055 from the problem.
Keq expression is
Keq = (NO2)^2/(N2O4)

If 0.400-x = 0.0055, then x = 0.3945
So (N2O4) = 0.0055
and NO2 = 2x = 0.3945*2 = 0.789

Now substitute into Keq above to obtain:
Keq = (0.789)^2/(0.0055) = ??
about 113 or so.

I got the problem from my book, and it says the answer is 0.87?

To set up this problem, we need to use the given information about the amount of N2O4 and its decomposition at equilibrium to determine the equilibrium constant, Keq.

First, let's define the equilibrium expression for this reaction:

Keq = [NO2]^2 / [N2O4]

Where [NO2] and [N2O4] represent the concentrations (in mol/L) of NO2 and N2O4, respectively, at equilibrium.

Given that 0.400 mol of N2O4 was initially charged and 0.0055 mol remains at equilibrium, we can calculate the concentration of N2O4 remaining:

[N2O4] = (0.0055 mol) / (1.00 L) = 0.0055 M

Since the stoichiometry of the reaction is 1:2 between N2O4 and NO2, the concentration of NO2 will be twice that of N2O4 remaining:

[NO2] = 2 * [N2O4] = 2 * (0.0055 M) = 0.011 M

Now we can substitute these values into the equilibrium expression:

Keq = (0.011 M)^2 / (0.0055 M)

Simplifying this expression:

Keq = 0.121 M / 0.0055 M

Keq = 22.0

Therefore, the equilibrium constant (Keq) for this reaction at 373 K is 22.0.