WAEC Chemistry Practical Questions and Complete Answers 2021 : Current School News

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WAEC Chemistry Practical Questions and Complete Answers 2021

Filed in Exam, WAEC News by on September 17, 2021

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– WAEC Chemistry Practical Questions –

WAEC Chemistry Practical Questions which is very tough has been simplified here. This is so since we have provided in this article WAEC expo questions for Chemistry Practical and past random repeated questions for free. Stay focused on this page to see them below.

WAEC 2021 Chemistry Practical Questions

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 examination in West African countries.

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

WAEC 2021 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 f 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
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
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 colourless 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 colourless and odourless 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)
The occur as a result of the decrease in the concentration of 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 become 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 dissolve 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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