West African Examinations Council
WASSCE Chemistry · Paper 3 — Practical
Sat separately from the written papers.
8 exam-style questions, written to the West African Examinations Council format and free to read. The answers are here too — what they do not tell you is how many you would get right with a clock running.
1. Equal masses of marble chips were reacted with excess dilute hydrochloric acid: in one flask as large lumps and in another as powder.
(a) State which reaction would finish first and explain why. [8 marks]
(b) Describe how you would measure the rate of each reaction. [8 marks]
(c) State two variables that must be kept constant for the comparison to be valid. [4 marks]
2. Carbon(IV) oxide is to be prepared in the laboratory.
(a) Name the two reagents used and write the equation for the reaction. [6 marks]
(b) Describe how the gas would be collected and state why that method is chosen. [8 marks]
(c) Describe a test that confirms the gas is carbon(IV) oxide, giving the observation. [6 marks]
3. A portion of specimen J is warmed with dilute hydrochloric acid and the gas evolved is passed through lime water.
(a) State what would be observed in the test tube and in the lime water. [6 marks]
(b) Identify the gas evolved and the anion present in J. [6 marks]
(c) Write the equation for the reaction occurring in the lime water. [8 marks]
4. A mixture contains sand, common salt and iodine.
(a) Describe, in order, how you would obtain each component separately. [12 marks]
(b) Name the physical property exploited at each stage. [6 marks]
(c) State one precaution when handling iodine. [2 marks]
5. A saturated solution of potassium trioxonitrate(V) was prepared at 60 °C and allowed to cool slowly.
(a) State what would be observed as the solution cools. [5 marks]
(b) Explain the observation in terms of solubility. [7 marks]
(c) Describe how you would obtain a dry sample of the crystals formed. [8 marks]
Reading these is not the same as sitting them.
Every question above is answerable given time. The exam does not give you time. Sit the whole paper on the real clock and the number you get back is the one that means something.
Sit it against the clock — freeExampaper is an independent study service. It is not affiliated with, endorsed by, or connected to WAEC, NECO, JAMB or any examination body. Exam names and subject titles are used only to describe what each paper is for.