Equilibrium 2

Question 1

Units of eqbm

Answer 1

1. if ∆ ng=0 then no unit
2. if ∆ ng ≠0, then unit depends on reaction (mol/l)

Question 2

How reaction quotient helps in determining the direction of the reaction.

Answer 2

1. When K=Q
   This is a state of equilibrium because the concentration of reactants and products are equal.
2. Q<K
   This means that equilibrium is not established yet
   [R]>[P]
   and the reactants has a tendency to form products. Therefore, reaction is proceeding in the forward direction.
3. When Q>K
   This means that equilibrium is not established yet
   [R]<[P]
   in order to establish equilibrium the reaction will proceed in the backward direction

Question 3

Le chaterlier’s principle

Answer 3

According to this principle if a system at equilibrium is subjected to change in temperature, concentration, pressure etc… then equilibrium shifts in the direction that tends to undo the effect of change.

Question 4

Factors affecting equilibrium constant

Answer 4

1. Effect of concentration.
   A<->B

if the concentration of a is increased the reaction proceeds in the forward direction so as to decrease the concentration of A and vice versa.

2. Effect of Pressure
   A+B<-> C+2D
   If pressure is increased, reaction proceeds in the forward direction of lesser number of moles. In this case the reaction will proceed in the backward direction on the contrary if pressure is decreased, the reaction will proceed in the forward direction.
3. Effect of temperature
   A<->B
   An endothermic reaction is favored by increase in temperature and exothermic reaction is favored by decrease in temperature.
   if ∆H=-ve (exothermic)
   if ∆H=+ve (endothermic)
4. Effect of catalyst
   A catalyst has no effect on equilibrium but rather only increases or decreases the rate of reaction.
5. Effect of volume
   Volume is inversely proportional to the pressure as per Boyle’s law. Hence an increase in volume favors the side, where the number of moles is more.
6. Introduction of an inert gas
   - If V is constant and ∆n=0 then no effect
   - if V is not constant, ∆n=0 then no effect
   - if V is not constant, ∆n=+ve then reaction proceeds in the forward direction.
   - if V is not constant, ∆n=-ve then reaction proceeds in the backward direction.

Question 5

Define an acid and base based on Arrhenius concept.

Answer 5

1. An acid is a substance which can release H+ ions.
2. A base is a substance which can donate OH- ions.

Question 6

Why was the Arrhenius concept proved to be not practical?

Answer 6

It was later found that, all bases don’t fall under this ategory as for example, NH3 is basic but does not have OH-.

Question 7

Define an acid and base based on Bronsted-Lowry theory concept.

Answer 7

1. An acid is a substance which can donate, H+ or H3O+ ions.
2. Base is a substance which can accept H+ or H3O+ ions.

According to this Theory,
- every acid produces a conjugate base and every base produces a conjugate acid. Thus they form a conjugate acid-base pair.
- Every strong acid produces a weak conjugate base and a strong base produces a weak conjugate acid.

Question 8

Formula for CA and CB

Answer 8

Acid - H+ -> CB
Base + H+ ->CA