Question

1. Given the following relationships, how would the reaction shift to establish or maintain equilibrium? a. Q>K

   b. Q<K c. Q=K

2. How would the equilibrium shift given the following stresses on the following reaction? A (l) + B (g) ↔ 2C (g) + D (l) ΔH = 145 kJ

   1. Removal of compound D

   2. Increase in temperature

   3. Decrease in pressure

3. Indicators are usually organic molecules with functional groups that will accept or donate protons to the solution which will change the structure and make the solution change color. How does the precision of a pH measurement done with an indicator compare to that of pH paper or a pH probe?

Answer 1

1)

Q = Reaction quotient , it gives ratio of products to reactants at any given point of time

Kc = Equilibrium constant , iti gives ratio of products to reactants at equilibrium

a) If Q > K, more products than reactants

Hence, the reaction shift to left to maintain equilibrium.

b) If Q < K, more reactants than products

   Hence, the reaction shift to right to maintain equilibrium.

If Q=K, the reaction is at equilibrium. The reaction neither shift right nor left.

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2) Given reaction is A (l) + B (g) ↔ 2C (g) + D (l) ΔH = 145 kJ

Since ΔH is + ve, the reaction is endothermic

a) Removal of products favours the forward reaction so that more products will be formed.

Hence, removal of D shift the equilibrium to right.

b) Endothermic reactions favored by increase of temperature.

Hence, Increase in temperature shift the equilibrium to right.

c) Decrease in pressure favours the side which has more no of moles.

Hence, Decrease in pressure shift the equilibrium to right.

Here, 2 moles of reactants  -----> 3 moles of products