x = 0 means we are already at equilibrium. So far so good, but if I want to calculate the hydrogen (0,5-3x)

^{3} = c(H

_{2}) we get 0.125 mol/l but we put 0.5 mol/l in?

?

For ammonia (1+2x)

^{2} = c(NH

_{3}) give 1 mol/l and also for nitrogen (1-x) give 1 mol/l. Why it doesnt fit for hydrogen.

the whole term give 1/0.125 = 8 = K