10 - Chemical equilibrium

Question 1

What is a reversible reaction?

Answer 1

• a reaction which can go in two directions.

- the forward and reverse reaction both occur at the same time but not necessarily at the same time.

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.
• concentration of the reactants and products remain constant.
• reaction has reached a position of equilibrium.

Question 3

What is a closed system?

Answer 3

• it is a system where no chemicals can go 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

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

Question 6

If pressure was increased, what happens to the point 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 point of equilibrium?

Answer 7

• position of equilibrium will shift in the opposite direction.

Question 8

Equilibrium constant Kc expression?

Answer 8

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