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Leaving Cert Chemistry: Chemical equilibrium

How often Chemical equilibrium comes up on the Chemistry papers, every year it was asked, and questions to try.

HL Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker

OL Asked on 10 of the last 10 Ordinary Level papers, most recently in 2026. banker

June 2027 is the first exam on the new Chemistry course. These come from the 2016–2026 papers, so read them as a guide.

Chemical equilibrium, Higher Level(8 marks)

Quick ones on Chemical equilibrium.

(a)At dynamic equilibrium, the rates of the forward and reverse reactions are?
  1. Both zero
  2. Equal
  3. Forward faster than reverse
(b)The forward reaction is exothermic. Effect of raising the temperature on the yield of product?
  1. The yield is unchanged
  2. The yield increases
  3. The yield decreases
(c)Effect of increasing the pressure on N2 + 3H2 in equilibrium with 2NH3?
  1. The equilibrium shifts to the right, making more ammonia
  2. There is no change, as only the catalyst controls the yield
  3. The equilibrium shifts to the left, making less ammonia
Show the answers

(a) Equal

(b) The yield decreases

(c) The equilibrium shifts to the right, making more ammonia

Your turn: Higher Level questions on Chemical equilibrium.

Higher Level

Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q7
2025Q9
2024Q7
2023Q9
2022Q7
2021Q9
2019Q11(b)
2018Q9
2017Q7
2016Q7

Links open the State Examinations Commission’s paper for that year.

More Chemical equilibrium questions

Chemical equilibrium, 2 marks

Which change alters the value of Kc for a reaction?

  1. Adding a catalyst
  2. A change in pressure
  3. A change in temperature
Show the answer

A change in temperature

Kc is constant at a given temperature. Pressure and concentration changes shift the position, but only temperature changes Kc.

Chemical equilibrium, 3 marks

2CrO4 2- + 2H+ in equilibrium with Cr2O7 2- + H2O. NaOH is added to the orange solution. It turns?

  1. Green, as chromium is reduced
  2. Yellow, as H+ is removed
  3. A deeper orange
Show the answer

Yellow, as H+ is removed

OH- removes H+, so the equilibrium shifts left to replace it, forming yellow chromate ions.

Chemical equilibrium, 3 marks

Pink cobalt ions form blue [CoCl4]2- in an endothermic reaction. Heating the pink mixture turns it?

  1. Blue
  2. Paler pink
  3. Colourless
Show the answer

Blue

Heating favours the endothermic direction, which absorbs heat. The equilibrium shifts towards the blue complex.

Ordinary Level

Asked on 10 of the last 10 Ordinary Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q9
2025Q11(c)
2024Q10(b)
2023Q11(b)
2022Q10(b)
2021Q11(b)
2019Q10(b)
2018Q11(b)
2017Q11(a)
2016Q11(a)

Links open the State Examinations Commission’s paper for that year.

More Chemical equilibrium questions

Chemical equilibrium, 2 marks

Colour change when concentrated HCl is added to pink cobalt(II) chloride solution?

  1. Pink to colourless
  2. Blue to green
  3. Pink to blue
Show the answer

Pink to blue

Extra chloride ions push the equilibrium towards the blue chloride complex, as Le Chatelier's principle predicts.

Chemical equilibrium, 2 marks

Adding more of a reactant to a system at equilibrium moves the equilibrium?

  1. Nowhere, it has no effect
  2. To the right, forming more product
  3. To the left, forming more reactant
Show the answer

To the right, forming more product

The system opposes the change by using up some of the added reactant.

Chemical equilibrium, 2 marks

Colour change when acid is added to yellow potassium chromate solution?

  1. Yellow to orange
  2. Yellow to green
  3. Yellow to colourless
Show the answer

Yellow to orange

Added H+ ions shift the chromate and dichromate equilibrium towards orange dichromate. Adding alkali reverses it.

Other Chemistry topics

All of Leaving Cert Chemistry