Topic 10 - Chemical Equilibrium

Question 1

what is a reversible reaction?

Answer 1

• a reaction which can go in two directions.

- the reactants can react to form products and the products can react to form the original reactants.

Question 2

what is dynamic equilibrium?

Answer 2

• in a closed system
• when the rate of the forward reaction is equal to the rate of the reverse reaction.
• At dynamic equilibrium, concentration of the reactants and products remains constant.
• reaction has reached a position of equilibrium.

Question 3

what is a closed system?

Answer 3

it is a system where no chemicals/substances can move in or out of the apparatus.

Question 4

what can disturb position of equilibrium?

Answer 4

• change in pressure of a gaseous reaction
• changing concentration of reactants/products in an aqueous reaction
• change in temperature of the system.

Question 5

if temperature is increased in the system, what happens to the position of equilibrium?

Answer 5

• temperature increase shifts the position of equilibrium in the endothermic direction to lower the temperature.

Question 6

if pressure was increased, what happens to the position of equilibrium?

Answer 6

• position of equilibrium shifts to the side with less gas molecules to lower the pressure.

Question 7

If concentration of reactant/product was increased, what happens to the position of equilibrium?

Answer 7

• position of equilibrium shifts in the opposite direction to lower the concentration of the reactant/product.

Question 8

equilibrium constant Kc expression?

Answer 8

• Kc = products/reactants
• use square brackets.
• square each substance if there is more than one molecule
• include state symbols inside square brackets.
• to find units, replace substances in formula with units (moldm-3).
• treat like fraction and divide if needed.
• sometimes there are no units.