Le Chateliers principle

Question 1

What is Le Chatelier’s principle ??

Answer 1

is the idea that if you change the conditions of a reversible reaction at equilibrium , the system will try to counteract the change.

• It can be used to predict the effect of any changes you make to a reaction system

Question 2

Such as changes to the temperature..

Answer 2

• All reactions are endothermic in one direction and exothermic in the other direction.
  2) Decrease temperature = equilibrium will move to exothermic direction to produce more heat = more products for exothermic reaction and fewer for endothermic reaction

3) if you raise temperature , the equilibrium will move to the endothermic direction to try and decrease it = you’ll now need more products for the endothermic reaction and fewer for exothermic reaction

Question 3

N2 + 3H 2 ⇌ 2NH3 (temp)

Answer 3

forward reaction is exothermic, decrease in temp moves it to right

Question 4

Changes to pressure ( only affects equilibriums involving gases)

Answer 4

1) decrease pressure = The equilibrium tries to increase it - moves to direction where there is more molecules of gas

2) Increase pressure = equilibrium tries to reduce it - moves to direction where there is less molecules of gas

3) you can use balanced symbol equation to work out which side has more molecules of gas

Question 5

N2 + 3H 2 ⇌ 2NH3 (pressure)

Answer 5

• 4 moles on left, 2 on right ,increase pressure = equilibrium shifts to right

Question 6

Changes to concentration

Answer 6

• If you change the concentration of either reactants or products, the system will no longer be at equilibrium so the system responds to bring itself back to equilibrium.
• increase concentration of reactants = the system will decrease it by making more products
• Decrease concentration of products = system will increase it by reducing amount of reactants

Question 7

N2 + 3H 2 ⇌ 2NH3 ( conc)

Answer 7

If you N2 or H2 is added, forward reaction increases to produce more NH3