Practical 1: Paper 3 format, apparatus, safety and titration technique

Every WASSCE and NECO SSCE chemistry candidate sits a practical paper. It is short in hours but heavy in marks, and it is the paper where well-drilled students gain the most. WAEC calls it Chemistry Paper 3. School candidates sit a 2-hour practical test in a laboratory; private (GCE) candidates sit a 1 hour 30 minutes “alternative to practical” paper, in which the readings and observations are printed and you analyse them. Each version has three compulsory questions and carries 50 marks.

• Question 1: quantitative analysis, almost always a titration (acid–base or redox) followed by calculations. It is the biggest question, usually just under half the paper.
• Question 2: qualitative analysis, the identification of a salt or a mixture of salts by a series of tests written up as a three-column table of test, observation and inference.
• Question 3: familiarity with practical activities from the teaching syllabus: apparatus, separation techniques, preparation and collection of gases, safety, rates, heats of reaction, organic tests and short calculations such as dilution.

NECO calls the practical Chemistry Paper I (paper code 2021). In recent NECO timetables it lasts 2 hours; the external (November/December) series lists it as an alternative to practical. NECO follows the same national senior secondary curriculum, and its questions follow the same three-part pattern: a titration, a salt analysis and a question on practical activities.

How marks are shared

A recent WAEC marking scheme gave about 24 marks to the titration question, about 15 to the salt analysis and about 11 to the third question. In the titration, a large block of marks (in one scheme, 8 marks for two concordant titres and 2 for averaging) is awarded for the table of burette readings alone, before any calculation. A student who tabulates well and whose titres are close to the supervisor’s value banks those marks even if the calculation later goes wrong. Treat these exact numbers as typical, not fixed: the council can change the split from year to year.

The instructions on the cover

The rubric is short and every line matters. Typical lines are: “All your burette readings (initial and final) as well as the size of your pipette must be recorded, but no account of experimental procedure is required. All calculations must be done in your answer booklet.” And for the analysis: “Credit will be given for strict adherence to the instructions, for observations precisely recorded and for accurate inferences. All tests, observations and inferences must be clearly entered in your answer booklet, in ink, at the time they are made.” Read them as a mark scheme in disguise: tabulate every reading, state the pipette size, record observations as you see them, and write inferences that follow from them.

Specimens and the supervisor

Some weeks before the paper, schools receive “instructions to supervisors” listing the solutions to prepare (for example, a dilute acid in a bottle labelled A, a solution of sodium hydroxide labelled B and a solid salt labelled C). The chemistry teacher must carry out the titration on the day and report the titre on a supervisor’s report form; your titres are compared with that value. This is why you cannot “guess” a titre: accuracy is checked against a real measurement made with the same solutions.