Chemical Equilibrium

Question 1

What is Chemical Equilibrium?

Answer 1

: A state in which the rates of the forward and reverse reactions are equal
and the concentrations of the reactants and products remain constant.

Question 2

Explain law of mass of action.

Answer 2

The value of the equilibrium constant expression, Kc, is constant for a
given reaction at equilibrium and at a constant temperature.

Question 3

If the Kc value is large (Kc&raquo_space; 1)

Answer 3

the equilibrium lies to the right and the reaction mixture
contains mostly products.

Question 4

If the Kc value is small (Kc «1)

Answer 4

the equilibrium lies to the left and the reaction mixture
contains mostly reactants.

Question 5

If the Kc value is close to 1 (0.10 < Kc < 10)

Answer 5

the mixture contains appreciable amounts of both
reactants and products.

Question 6

Reactants and products exist in a single phase.

Answer 6

Homogeneous equilibria

Question 7

Reactants and products are present in more than one phase.

Answer 7

Heterogeneous equilibria

Question 8

Solids and liquids are incorporated in the Kc value; they are not
part of the variable Kc expression:

Answer 8

Because pure solids and liquids: concentrations of pure solids and liquids are fixed by their density and
molar mass (both constants) and do not vary with the amount.

Question 9

If a system at equilibrium is disturbed by an external stress, the
system adjusts to partially offset the stress as the system attains a new equilibrium position.

Answer 9

Le Chatelier’s Principle:

Question 10

a substance that, when dissolved in
water, increases the concentration of H+ ions.

Answer 10

Acid

Question 11

a substance that, when dissolved in
water, increases the concentration of OH- ions.

Answer 11

Base