Equalibrium Concentrations

Question

The equilibrium constant, K_c, for the following reaction is 1.80×10^-4 at 298 K.

NH₄HS(s) NH₃(g) + H₂S(g)

Calculate the equilibrium concentration of H₂S when 0.390 moles of NH₄HS(s) are introduced into a 1.00 L vessel at 298 K.

[H₂S] =  _______M

Answer 1

Kc == [NH3][H2S] Note: NH4HS is not part of the equilibrium expression as it is a solid.

1.8E-04 = (0.390 -x)(0.390 - x)

1.8E-04 = (0.390 - x)^2

sq rt(1.8E-04) = 0.390 - x

0.013 = 0.390 - x x = 0.390 - 0.013 = 0.377

[H2S] = 0.390 - 0.377 = 0.013M