Posted by Rob on .
When heated, N2O4 dissociates as follows: N2O4 =2NO2
A flask initially contians .560 M N2O4. at this temperature, Kc is 4.00. what is the equilibrium concentration of NO2?

Chemistry 
DrBob222,
Set up an ICE chart, substitute into Kc, and solve.
initially:
N2O4 = .560 M
NO2 = 0
change:
NO2 = +2x
N2O4 = x
equilibrium:
N2O4 = 0.560x
NO2 = 2x
Solve for x, then 2x will be (NO2). Post your work if you get stuck. 
Chemistry 
Rory,
i ended up with x=.28 and i multiplied it by 2 and it was not the right answer