I feel like I know what I'm doing but I'm not getting an answer that is offered. Heres the question:(adsbygoogle = window.adsbygoogle || []).push({});

Dinitrogentetraoxide partially decomposes according to the following equilibrium:

N2O4 (g) ---> 2NO2 (g) (an arrow going other way too)

A 1.00-L flask is charged with .400 mol of N2O4. At equilibrium at 373 K, 0.0055 mol of N2O4 remains. Equil. constant for this reaction is __________.

a. 2.2 x 10^-4

b. 13

c. 0.22

d. 0.022

e. 0.87

K = [NO2]^2 / [N204]

N2O4 goes from .4 to .0055 mol, so that is a change of .3945 mol, which must be the equilibrium amount of the 2NO2. Since the volume is just 1 L

K = [.3945 M]^2 / [.0055 M] = 28.3

but this is not one of the choices.

what am I doing wrong?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Chemistry - calculating equilibrium constant, what am I doing wrong?

**Physics Forums | Science Articles, Homework Help, Discussion**