Le Chatelier's Principle

Question 1

what does le chateliers principle state

Answer 1

• if there is a change in the concentration, pressure or temperature in a reversible reaction
• the equilibrium position will move to counteract that change

Question 2

what is special about equilibrium reactions when using temperature a factor that can change the equilibrium reaction

Answer 2

• all reactions are exothermic in one direction

- but endothermic in the other direction

Question 3

what happens if you decrease the temperature in a reversible reaction

Answer 3

• the equilibrium will move in the exothermic direction

- to produce more heat

Question 4

what happens if you increase the temperature in a reversible reaction

Answer 4

• the equilibrium will move in the endothermic direction

- to absorb the extra heat

Question 5

how is the reaction N2 + 3H2 = 2NH3, a reversible reaction, affected by temperature change

Answer 5

• the reaction is exothermic in the forward direction
• so if you decrease the temperature the equilibrium will shift to the right
• therefore producing more product

Question 6

what do changes in pressure only affect

Answer 6

reversible reactions and equilibria involving gases

Question 7

what happens when you increase the pressure in a reversible reaction

Answer 7

• the equilibrium will move towards the side that has fewer moles of gas
• to reduce the pressure

Question 8

what happens when you decrease the pressure in a reversible reaction

Answer 8

• the equilibrium will move towards the side that has more moles of gas
• to increase the pressure

Question 9

how is the reaction N2 + 3H2 = 2NH3, a reversible reaction, affected by pressure change

Answer 9

• the reaction has 4 moles of gas on the left and 2 on the right
• so if you increase the pressure, the equilibrium will shift to the right
• therefore producing more product

Question 10

what happens when you increase the concentration of reactants in a reversible reaction

Answer 10

• the equilibrium will shift to the right
• to use up the reactants
• therefore making more product

Question 11

what happens when you increase the concentration of products in a reversible reaction

Answer 11

• the equilibrium will shift to the left
• to use up the products
• therefore making more reactants

Question 12

what would decreasing the concentration of reactants or products simply do

Answer 12

• have the opposite effect

- like what would happen if the concentration of the other were to be increased

Question 13

why do industries apply le chateliers principle to their reversible reactions

Answer 13

• to work out how changing the conditions will affect the equilibrium position
• you can increase the yield of the reaction by changing specific conditions to shift the equilibrium to the right
• producing more product than you would if you didnt know or apply the principle