WAEC Chemistry Practical Questions and Answers in 2024

Filed in Exam, WAEC News by on February 22, 2024

WAEC Chemistry Practical Questions that seem quite difficult have been simplified here. You don’t have to worry about how and where to receive a study guide for your upcoming exams because we’ve got it covered.

The West African Examinations Council (WAEC) is an examination board that conducts the West African Senior School Certificate Examination (WASSCE), for University and Jamb entry examinations in West African countries.

In a year, over three million candidates register for the exams coordinated by WAEC.

WAEC 2024 Chemistry Practical Questions

(1.) Volume of burrete = 50.00cm³
Volume of pipette = 25.00cm³
Indicator = Methyl orange.
 
TABULATE

Final burette readings (cm³); 37.50 | 22.50 | 37.50 | 44.50
Initial burette readings(cm³); 0.00 | 0.00 | 0.00 | 0.00
Volume of Acid used (cm³); 37.50 | 22.50 | 22.50 | 22.50
Volume of A used = 1st + 2nd + 3rd/3
= 22.50+22.50+22.50/3
The average volume of A used = 22.50cm³.

(1bi)
Concentration of A ( CA )?
2.03g in 500cm³ of solution
Volume = 500cm³/1000 = 0.500dm³
In g/dm³ = 2.03/0.5 = 4.06g/dm³
To find concentration in mol/dm³
Conc. of A in mol/dm³ = Conc. of A in g/dm³/Molar mass.
Conc. of A in mol/dm³ = 4.06/36.5
= 0.1112mol/dm³
The molar mass of A (HCL) = 1+35.5 = 36.5g/mol.

(1bii)
Number of mole of the Acid in average titre
Na = CaVa
= 0.1112 × 22.50
= 2.52moles.

(1biii)
Nb= ? Na= 3, Ca= 0.1112mol/dm³, Cb = 0.12mol/dm³ , Va = 22.50cm³, Vb = 50.00cm³.
CaVa/CbVb= nA/nB
0.1112×22.50/0.12×50 = 3/nB
nB × 2.502 = 18 nB = 18/2.502 = :. nB = 7.194moles = 7moles(approx.)

(1biv)
Mole ratio of Acid to base
nA:nB = 7:3

(2a)
Test; C + 10cm³ of distilled water + filter.
Observation; C dissolves partially to give a light green solution. Blue filtrate and green residue.
Inference: C is a mixture of soluble and insoluble salt.

(2bi)
Test; 2cm³ of filtrate + NaOH in drops in excess.
Observation: Blue precipitate remains.
Inference; CU²+ is present.

(2bii)
Test; 2bi + warm.
Observation: a colorless gas with a choking smell that turns moist red litmus blue and forms dense white fumes with hydrogen chloride gas.
Inference; NH³ from NH⁴+.

(2biii)
Test; 2cm³ of filtrate + BaCl² + excess HCl.
Observation: white precipitate, precipitate remains.
Inference; SO²- CO3²- or SO4²- is present, SO4²- confirmed.
(2ci)
Test; Residue + HNOg.
Observations: effervescence of a colorless and odorless gas, which turns like water milky and turns moist blue to litmus red.
Inference; CO2 from CO3²-

(2cii)
Test; 2ci + NH3 in drops in excess
Observations: blue precipitate. Precipitate dissolved to give a deep blue solution.
Inference; CU2+ present.
CU2+ confirmed.

(3ai)
The value will increase.

(3aii)
This occurs as a result of the decrease in the concentration of the base due to the added volume of water.

(3bi)
There will be no visible reaction because copper is less than Zinc in the electrochemical series.

(3bii)
It absorbs water and becomes sticky because it is hygroscopic.

(3biii)
The solution turns pink.

(3c)
When NaOH is added to the solution of zn³+, a white precipitate is formed which later dissolves in excess NaOH due to the formation of zinc hydroxide.

DISCLAIMER! These are not real WAEC Chemistry Practical questions, but likely repeated questions over the years to help candidates understand the nature of their examinations. Ensure to note every question provided on this page.

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