For the reaction `A+B hArr 3. C` at `25^(@)C`, a `3 L` vessel contains 1, 2, and 4 moles of A, B and C respectively. Predict the direction of reaction if:
a. `K_(c)` for the reaction is `10`.
b. `K_(c)` for the reaction is `15`.
c. `K_(c)` for the reaction is `10.66`

Answer

A, B, C, D

Explanation

`A+B hArr 3C`
Before reaction `[A]=1//3`
`[B]=2//3`
`[C]=4//3`
Thus,
`Q=([C]^(3))/([A][B])=(4^(3)xx3xx3)/(3^(3)xx1xx2)=64/6=10.66`
a. Since `K_(C)=10`, thus Q must decrease to attain `K_(c)` value and thus, [C] must decrease or [A] and [B] should increase. Thus, reaction will occur in backward direction.
b. Since `K_(C)=15`, thus Q must increase to attain `K_(C)` value and thus, [C] must increase or [A] and [B] must decrease. Thus, reaction will occur in forward direction.
c. `Q=K_(c)`, thus reaction is in equilibrium,