In: Chemistry
At 850K, the value of the equilibrium constant Kp for the ammonia synthesis reaction: N2(g)+H2(g)--> N2H2(g) is 0.3290. If a vessel contains an initial reaction mixture in which [N2]= 0.0200 M, [H2]=0.0200 M, and [N2H2]= 0.000150 M, what will the [N2H2] be when equilibrium is reached? The answer is not: 0.000298, .00681, .000172, .000148, .00031, .00471 please help!
initially
N2(g)+H2(g) <--> N2H2(g)
reaction quotient(Q) = [N2H2]/[N2][H2]
QC = 0.00015/(0.02*0.02) = 0.375
KP = KC(RT)^Dn
Dn = 1-2 = -1
R = 0.0821 l.atm.k-1.mol-1
T = 850 k
Kp = 0.329
0.329 = Kc*(0.0821*850)^-1
on solving
Kc = 22.96
Qc < Kc . so that forward reaction takes place
N2(g) + H2(g) <--> N2H2(g)
initial 0.02 M 0.02
M 0.00015 M
change x x x
equilibrium 0.02-x 0.02-x 0.00015+x
KC = [N2H2]/[N2][H2]
22.96 = (0.00015+X)/(0.02-X)^2
X = 0.005 M
so that,
at equilibrium
[N2H2] = 0.00015+x = 0.005+0.00015 = 0.00515 M