Question

Consider the following system at equilibrium:A(aq)+B(aq) <---> 2C(aq)Classify each of the following actions by whether it causes a leftward shift, a rightward shift, or no shift in the direction of the net reaction.1. Increase A- Right2. Increase B- Right3. Increase C- Left4. Decrease A- Right5. Decrease B- Right6. Decrease C- lEft7. Double A and Halve B- NO Shift8. Double both B and C- NO shift

Answer 1

Explanation:

Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.

This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

• On addition of reactant at equilibrium shifts the equilibrium in forward direction.
• On addition of product at equilibrium shifts the equilibrium in backward direction.
• On removal of reactant at equilibrium shifts the equilibrium in backward direction.
• On removal of product at equilibrium shifts the equilibrium in forward direction.

$A(aq)+B(aq)\rightleftharpoons 2C(aq)$

Reactants = A , B

Product = C

1. Increase A

On increasing the amount of A at equilibrium will shift the equilibrium in forward or rightward direction.

2. Increase B

On increasing the amount of B at equilibrium will shift the equilibrium in forward or rightward direction.

3. Increase C

On increasing the amount of C at equilibrium will shift the equilibrium in backward or leftward direction.

4. Decease A

On decreasing the amount of A at equilibrium will shift the equilibrium in backward or leftward direction.

5. Decease B

On decreasing the amount of B at equilibrium will shift the equilibrium in backward or leftward direction.

6. Decease C

On decreasing the amount of C at equilibrium will shift the equilibrium in forward or rightward direction.

7. Double A and Halve B

Equilibrium constant of the reaction = K

$K=\frac{[C]^2}{[A][B]}$

On doubling A and halving B, equilibrium constant of the reaction = K'

$K'=\frac{[C]^2}{[2A][\frac{B}{2}]}=\frac{[C]^2}{[A][B]}$

The value of equilibrium constant K' is equal to K, which means that equilibrium will not shift in any direction.

8. Double both B and C

Equilibrium constant of the reaction = K

$K=\frac{[C]^2}{[A][B]}$

On doubling B and C, equilibrium constant of the reaction = K'

$K'=\frac{[2C]^2}{[A][2B]}=\frac{4[C]^2}{[A][2B]}=\frac{2[C]^2}{[A][B]}$

K' = 2 K

The value of equilibrium constant K' is double the K, which means that product is increasing which means that equilibrium will shift in backward or leftward direction.