Question

Dinitrogen tetroxide decomposes to nitrogen dioxide:
N2O4(g)→2NO2(g)ΔHorxn=55.3kJ
At 298 K, a reaction vessel initially contains 0.100 atm of N2O4. When equilibrium is reached, 58% of the N2O4 has decomposed to NO2. What percentage of N2O4 decomposes at 350 K ? Assume that the initial pressure of N2O4 is the same (0.100 atm).

Answer 1

There may be a shorter way to do this but off the top of my head here is what I think you need to do. Post your work if you get stuck.

.......N2O4 ==> 2NO2
I......0.1........0
C...-0.058*0.1..+0.058*0.1
E......?...........?

Solve for Keq which I will call k1. That gives you k at 298 K.

Now use the van't Hoff equation of
ln(k2/k1) = dHo(1/T1-1/T2)/R
and solve for k2 at 350K.

Go back to the ICE and redo that in reverse to find how much N2O4 is left at equilibrium and from that you get % decomposition.