At `1400 K, K _(c) = 2. 5 xx 10 ^(-3)` for the reaction. `CH _(4)(g) + 2H _(2) S (g) hArr CS _(2) (g) + 4 H _(2)(g)` A 10L reaction vessel at 1400 K contains 2.0 mol of `CH_(4)3.0` mol of C`S_(2)3.0` mol of H, and 4.0 mol of `H_(2) S.` In which direction does the reaction proceed to reach equilibrium?

Options

A. Forward
B. Backward
C. May be forward or backward
D. Reaction is in equilibrium

Answer

B

Explanation

`CH_(4)(g) + 2H_(2)S(g) overset(K)hArr CS_(2)(g) + 4H_(2)(g)`
or `K = ([CS_(2)][H_(2)]^(4))/([CH_(4)][H_(2)S]^(2))` ....(i) `[CS_(2)] = ((3)/(10)), [H_(2)] = ((3)/(10)), [CH_(4)] = ((2)/(10))` and `[H_(2)S] = ((4)/(10))`
Substituting all the concentration values in equation (i) `K = (((3)/(10))((3)/(10))^(2))/(((2)/(10))((4)/(10))^(2)) = (3^(5))/(10^(5)) xx (10^(3))/(2 xx 4^(2)) = (243)/(3200) = 75.94 xx 10^(-3)`
Therefore, `K gt 2.5 xx 10^(-3)` (given). Hence, the reaction will proceed in backward direction.