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    Categories: Waec

Chemistry 3 (Practical) (Alternative A) 09:30 hrs. – 11:30 Tuesday april 3rd

Tuesday, 3rd April, 2018
Chemistry 3 (Practical) (Alternative A)
Chemistry 3 (Practical) (Alternative A)
09:30 hrs. – 11:30

Answers will be posted just make sure u refresh after 5minutes ok

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*WAEC 2018 CHEMISTRY PRACTICAL ANSWERS*

1)
Tabulate
Burette reading|Final burette reading
(cm^3)|Initial burette reading (cm^3)|
Volume of acid used(cm^3)|
Rough- 24.10,0.00,24.10
First- 23.80, 0.00, 23.80
Second- 23.75, 0.00, 23.70
Third- 23.75, 0.00, 23.75
Average volume of A used = 23.80 + 23.70 + 23.75cm^3/3
=23.75cm^3

2a)
-Observation-
part of the C dissolves,colourless filtrate salt

-Inference-
C is a mixture of soluble salt

2bi)
-observation-
white precipitate formed

-Inference-
Cl is present

2bii)
-Observation-
precipitate dissolves

-Inference-
Cl confirmed

2biii)
-Observation-
colourless gas evolved with characteristic choking smell, turns litimus paper blue

-Inference-
Gas is NH3

2c)
-Observation-
Residue dissolves liberating a colourless gas which turns lime water milky

-Inference-
gas is CO2
CO^2-3 present

3a)A white precipitate of barium sulphate will be formed by the instant reaction between barium chloride and sulphuric acid.

BaCl2 + H2SO4 = BaSO4 + 2HCl

3b)Iron sulfide reacts with hydrochloric acid, releasing the malodorous (rotten egg smell) and very toxic gas,hydrogen sulphide. FeS + 2 HCl → FeCl2+ H2S

3c)When solid iron filings are added to dilute aqueous Hydrochloric acid, Iron (II)chloride or ferrous chloride is formed , with the liberation of Hydrogen gas.

Fe (s) + 2HCl (aq) ……..> FeCl2(aq) + H2 (g)
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Pls Use Your School End Point.

1a)
Volume of pepette = 25.00Cm^2
Indicator Used = Methyl Orange
Tabulate
BURETTE READING|ROUGH|1ST|2ND|3RD|
Final reading Cm^3|25.00|34.00|29.20|24.10|
Initial Reading Cm^3|0.00|10.00|5.00|0.00|
Volume Of Acid Used In Cm^3|25.00|24.00|24.20|24.10|
Average Volume of Acid used =(24.00+24.20+24.10/3)cm^3
=24.10cm^3
More coming keep refreshing.
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2a)
-Observation-
part of the C dissolves,colourless filtrate salt
-Inference-
C is a mixture of soluble salt

2bi)
-observation-
white precipitate formed
-Inference-
Cl is present

2bii)
-Observation-
precipitate dissolves
-Inference-
Cl confirmed

2biii)
-Observation-
colourless gas evolved with characteristic choking smell, turns litimus paper blue
-Inference-
Gas is NH3

2c)
-Observation-
Residue dissolves liberating a colourless gas which turns lime water milky
-Inference-
gas is CO2
CO^2-3 present

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3)

More Coming Soon.
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2 a)
– Observation-
part of the C dissolves, colourless filtrate
salt
– Inference –
C is a mixture of soluble salt
2 bi )
– observation –
white precipitate formed
– Inference –
Cl is present
2 bii )
– Observation-
precipitate dissolves
– Inference –
Cl confirmed

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