# 2021 WAEC GCE 2021nd series Chemistry Practical Answers : 2020 WAEC GCE 2nd series Chemistry Practical Answers Night before Exam

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(1a)
Mass number A = 1.85g
Vol of A = 250cm³
Mass of B =400g in 1dm³

Average title = 25.00+24.90/2

=49.90/2=24.95cm³

(1b)
(i) yellow
(ii) colourless

(1ci)
Conc of B in mol/dm³ ; ?
Mole =4.00/40 =0.1mol

Mole = conc * vol(dm³)
Conc =mole/vol
Conc =0.1/1
Conc=0.1mol/dm³
Conc of B =0.1mol/dm³

(1cii)
Cb=0.1mol/dm³ , Vb=25.0cm³ , Ca =? Va=24.95cm³
na=1, nb=1
CaVa/CbVb
Ca*24.95/0.1*25.0=1/1
Ca=0.1*25.0/24.95=2.5/24.95=0.100mol/dm³

(1di)
Molecular mass=?
Mass conc =1.85/250*1000
=7.4g/dm³
Conc(mol/dm³)=mass conc/molar mass
0.1=7.4/molar mass
Molar mass =7.4/0.1= 75g/mol

(1dii)
A=CnH²n+1COOH
CnH²n+1COOH=74
(12*n)+(1x(2n+1)+12+16+16+1=74
12n+2n+1+45=74
14n+46=74
14n=74-46
14/14=28/14
n=2
C²H⁵COOH

(1e)
This is because it is a reaction between weak acid and strong base

(1a to 1c)

(1
d to 1e)

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)
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(2a)
TEST
C(aq) + HCl

OBSERVATION
No gas evolved/No observable reaction

INFERENCE
SO²,⁴^- Some may be Present

(2b)
TEST
C+BaCl² + dili H²SO⁴

OBSERVATION
White Precipitate Formed Precipitate insoluble remain Undissolved

INFERENCE
SO²,⁴^- confirmed

(2ci)
TEST
C+NaOH(aq) In drop them in excess

OBSERVATION
No precipitate / No visibie reaction
No Observation reaction.

INFERENCE
Probably NH+⁴ Present

(2cii)
TEST
mixture in c(i) warmed

OBSERVATION
Gas is evolved
Gas is basic
Gas has a Pungent or smell

INFERENCE
NH₃ gas evowed hence NH³ presert

(2di)
TEST
C+HNO³ + AgNO³

OBSERVATION
No observable reaction
No gas evolved

INFERENCE
C1^- Present

(2dii)
TEST
Precipitate + HNO³

OBSERVATION
White precipitate
Precipitate insolubie

INFERENCE
C1^-confirmed

(2ei)
(i)(NH⁴)²SO⁴
(ii)NH⁴Cl

(2eii)
(i)Ammonium teraoxosulphate(iv) salt(NH⁴)²SO⁴)
(ii)NH⁴CI > Ammonium chloride

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)
==

(3ai)
There will be evolution of SO²

(3aii)
a green color is observed

(3aiii)
There is effervescence I:e CO² is liberated

(3b)
(i)HCl
(ii)Zn(OH) will dissolves readily while (⁴(OH)² will not.

(3c)
(i)it reduce the mass of the salt
(ii)to purity it

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)

2021 WAEC GCE 2021nd series Chemistry Practical Answers (ESSAY, OBJ, THEORY, PRACTICALS ETC)

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2021 EXAM DATES
NABTEB: 14th June - 9th July
NECO: 5th July - 16th August
WAEC: 16th August - 30th Sept

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Updated At: June 16th 2021, (02:06:25)