Mass action rato or reaction quotient Q for a reaction can be calculate using the law of masss action
`A(g)+B(g) hArr C(g)+D(g)`
`Q=([C][D])/([A][B])`
The value of Q decides whether the reaction is at equilibrium or not.
At equilibrium, `Q=K`
For an equilibrium process, `Q ne K`
when `Q gt K`, reaction will favour backward direction and when `Q lt K`, it will favour direction.
Answer the following questions:
For the reaction:
`2A+B hArr 3C` at `298 K, K_(c)=40`
A `4L` vessel contains `2, 1,` and `4` mol of A, B and c, respectively. The reaction at the same temperature

Options

A. Must proceed in forward direction
B. Must proceed in backward direction
C. Must be in equilibrium
D. Cannot be predicted

Answer

A

Explanation

`2A+B hArr 3C`
`[A]=("Mass")/("Volume")=2/4`
`[B]=1/4`
`[C]=4/4=1`
`:. Q=([C]^(3))/([A]^(2)[B])=((1)^(2))/((1/2)^(2)(1/4))=16`
Therefore `Q lt K_(c)` hence reaction will favour forward direction.