- Date: Thursday, 20th November, 2025
- Chemistry 3 (Alternative to Practical Work): 1hr 30mins – 13:00 hrs – 14:30 hrs
WAEC GCE Chemistry Practical Questions and Answers 2025 | Alternative to Practical Work Expo
SECTION A/B: ALTERNATIVE TO PRACTICAL CHEMISTY QUESTION
Instruction: Answer all questions in this section. Show clear reasoning and calculations where necessary.
Question 1
You are provided with the following solutions:
-
Solution A: Dilute hydrochloric acid (HCl)
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Solution B: Sodium hydroxide (NaOH)
(a) Describe how you would use these solutions to prepare a pure sample of sodium chloride (NaCl).
(b) Write a balanced chemical equation for the reaction.
Answer (Guide):
(a)
-
Measure equal volumes of HCl and NaOH using a burette.
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Mix both in a beaker until neutralization occurs (check with litmus paper).
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Evaporate the solution to dryness to obtain pure NaCl crystals.
(b)
Equation:
NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)
Question 2
(a) Define the term acid-base titration.
(b) State the appropriate indicators used for strong acid–strong base titrations.
Answer:
(a) Acid-base titration is a quantitative experiment used to determine the concentration of an unknown solution by reacting it with a known solution.
(b) Methyl orange or phenolphthalein is commonly used.
Question 3
The following results were obtained during a titration:
| Titration | Final burette reading (cm³) | Initial burette reading (cm³) | Volume of acid used (cm³) |
|---|---|---|---|
| 1 | 24.60 | 0.00 | 24.60 |
| 2 | 24.70 | 0.10 | 24.60 |
| 3 | 24.60 | 0.00 | 24.60 |
(a) Calculate the average titre value.
(b) Write the equation for the neutralization between NaOH and H₂SO₄.
Answer:
(a) Average titre = (24.60 + 24.60 + 24.60) ÷ 3 = 24.60 cm³
(b) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
Question 4
You are provided with an unknown salt C. Describe briefly how you would identify the following ions:
(a) Chloride (Cl⁻)
(b) Sulphate (SO₄²⁻)
(c) Carbonate (CO₃²⁻)
Answer:
(a) Add AgNO₃ solution - White precipitate (soluble in NH₃).
(b) Add BaCl₂ - White precipitate (insoluble in HCl).
(c) Add dilute acid - Effervescence due to CO₂ gas (turns limewater milky).
Question 5
State three differences between physical and chemical change observed in experiments.
Answer:
| Physical Change | Chemical Change |
|---|---|
| No new substance is formed | New substance formed |
| Reversible | Irreversible |
| Energy absorbed or released slightly | Energy change is large |
Question 6
When zinc granules react with dilute HCl, a gas is produced.
(a) Name the gas evolved.
(b) Write a balanced equation for the reaction.
(c) State one use of the gas.
Answer:
(a) Hydrogen gas
(b) Zn + 2HCl → ZnCl₂ + H₂
(c) Used in filling balloons and hydrogenation of oils.
Question 7
Describe one experiment to test for the presence of oxygen gas.
Answer:
-
Insert a glowing splint into a test tube containing the gas.
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The splint relights → Oxygen is present.
Question 8
Explain briefly how to test for water using:
(a) Cobalt(II) chloride paper
(b) Anhydrous copper(II) sulphate
Answer:
(a) Turns from blue to pink.
(b) Turns from white to blue.
Extra Practice Tips for WAEC GCE Chemistry Practical (Alternative to Practical Work)
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Revise standard laboratory apparatus and their uses.
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Practice calculation of molarity, molar mass, and percentage purity.
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Study qualitative analysis (anion & cation tests).
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Always write observations and inferences clearly during practicals.
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Conclusion
This post has provided the WAEC GCE Chemistry Practical (Alternative to Practical Work) Questions and Answers 2025 (Nov/Dec) to help you prepare confidently for the upcoming paper. Study carefully, revise titration and qualitative analysis steps, and ensure accuracy in your chemical equations.
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