Question

1 mol of CH₄, 1 mole of CS₂ and 2 mol of H₂S are 2 mol of H₂ are mixed in a 500 ml flask. The equilibrium constant for the reaction K_c = 4 x 10^-2 mol² lit^-2. In which direction will the reaction proceed to reach equilibrium?

Answer 1

CH₄(g) + 2 H₂S (g) ⇌ CS₂(g) + 4H₂(g)

K_c = 4 x 10^-2 mol² lit^-2

Volume = 500 ml = `1/2`L

[CH₄]_in = `(1 "mol")/(1/2 "L")` = 2 mol L^-1

[CH₂]_in = `(1 "mol")/(1/2 "L")` = 2 mol L^-1

`["H"_2"S"]_"in" = (2 "mol")/(1/2 "L")`= 4 mol L^-1

`["H"_2]_"in" = (2 "mol")/(1/2 "L")`= 4 mol L^-1

Q = `(["CS"_2]["H"_2]^4)/(["CH"_4]["H"_2"S"]^2)`

`= ([2][4]^4)/([2][2]^2)`

= 64 mol² lit^-2

Q > K_C.

∴ The reaction will proceed in the reverse direction to reach the equilibrium.