Equilibrium

Question 1

What does it mean to say the position of equilibrium lies to the right?

Answer 1

When the concentration of products at equilibrium is greater than the concentration of reactants.

Question 2

What does it mean to say the position of equilibrium lies to the left?

Answer 2

When the concentration of reactants at equilibrium is greater than the concentration of products.

Question 3

Define what is meant by dynamic equilibrium

Answer 3

A dynamic equilibrium is the state of a reversible reaction in which the rate of the forward reaction equals the rate of the backward reaction.

Question 4

Dynamic equilibrium is reached when the…

Answer 4

• Reversible reactions occur in a closed system.
• Concentration of the reactants remains constant. Concentration of the products remains constant.
• Rate of the forward reaction equals the rate of the backward reaction.

Question 5

When the concentration of a reactant in equilibrium increases…

Answer 5

When the concentration of a reactant in equilibrium increases, the yield of the
product increases and the reaction’s equilibrium position moves to the
right.

Question 6

When the pressure in a system increases…

Answer 6

the position of equilibrium moves to the side with fewer gas molecules

Question 7

When the temperature of a system is increased, the equilibrium position moves…

Answer 7

in the direction of the endothermic reaction.

Question 8

What is the equation for Kc?

Answer 8

Kc = [products] / [reactants]

Question 9

What is the expression for the equilibrium constant for this reaction?
CaCO3 (s) ⇌ CaO (s) + CO2 (g)

Answer 9

Kc = [CO2]
Because for a heterogeneous equilibrium, we don’t include substances in the solid state.

Question 10

Why don’t we include solids in the Kc expression?

Answer 10

If you have a solid, and you increase its amount you do change the rates of reactions. But a pure solid has no concentration because it is not dissolved in any solvent (that’s why we call it pure solid). So, basically you just increase the amount of your pure solid, and that will have an effect on the concentration of some other reactant or product.
(Concentration of solids remain constant).

Question 11

When is a system heterogeneous?

Answer 11

A system is heterogeneous when all the substances in the reaction aren’t in the same phase.

Question 12

What types of substance do we not include in the equilibrium equation?

Answer 12

• Solids
• Liquids

Question 13

What do we need to know to calculate the equilibrium constant?

Answer 13

Concentrations of reactants and products at equilibrium