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) + 2 H _(2) S (g) overset(K) hArr CS _(2) + 4 H _(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 vaues in equation `(i) K = (((3)/(10 ) ) ( (3)/(10)) ^(4))/(((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.