H2(g)  + F2(g)  Â
<===> 2HF(g)
initial        Â
0.33/10 = 0.033 MÂ Â Â Â Â 0.033
MÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0.03 M
change        Â
x                                       Â
x                          Â
2x
equil           Â
0.033-x                       Â
0.033 -
x                     Â
0.03+2x
Reaction quotient(Q) = [HF]^2/[H2][F2]
                                         Â
= 0.03^2/(0.033^2)
                                         Â
= 0.826
  K = 25
Q
at equilibrium
                Â
K = [HF]^2/[H2][F2]
                Â
25 = (0.03+2x)^2/(0.033-x)^2
    x = 0.02
concentration of H2 at equil = 0.033 - x
                                               Â
= 0.033- 0.02 = 0.013 M