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Chemical equilibria
JAMB Chemistry topic guide with 2 practice questions.
What to revise
- reversible reactions and factors governing the equilibrium position; dynamic equilibrium
- Le Chatelier's principle and its industrial applications
- equilibrium constant (simple examples: action of steam on iron; N2O4 ⇌ 2NO2); no calculation required
You should be able to
- identify the factors that affect the position of equilibrium
- predict the effect of each factor on the position of equilibrium
- specify industrial processes where Le Chatelier's principle is required
- determine the effects of these factors on the equilibrium constant
From JAMB's Chemistry syllabus official. Full syllabus →
eZine's published bank has 9 questions on this topic (counted 29 October 2026).
Practice questions
Question 1 · Chemical equilibria
Changing the pressure would have NO effect on the equilibrium position of which reaction?
Show answer and explanation
Answer: D. H₂(g) + I₂(g) ⇌ 2HI(g)
Pressure affects the position only when the numbers of gas moles on the two sides differ. For H₂ + I₂ ⇌ 2HI there are 2 moles of gas on each side. The Haber (4 → 2), contact (3 → 2) and N₂O₄ (1 → 2) equilibria all have unequal numbers of gas moles.
eZine practice question (original, teacher-reviewed)
Question 2 · Chemical equilibria
For the equilibrium N₂O₄(g) ⇌ 2NO₂(g), the equilibrium constant K is
Show answer and explanation
Answer: B. [NO₂]² / [N₂O₄]
K = [products]^coefficients / [reactants]^coefficients = [NO₂]²/[N₂O₄]. The inverted expression is for the reverse reaction; the coefficient 2 is a power, not a multiplier; omitting the power gives the wrong expression.
eZine practice question (original, teacher-reviewed)
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