2019/20 CHEMISTRY PRACTICAL PRIVATE WASSCE(GCE)NOV/DEC REAL,,,,EXPO,,,,, SURE,,,,RUNS,,, LEAKAGE ANF CONFIRM QUESTIONS AND ANSWERS FOR ALL COUNTRIES SUCH AS GHANA,,,, SIERRA LEONE,,,, GAMBIA,,, LIBERIA,,,AND NIGERIA

2019 Waec Gce Chemistry Practical Answer.
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(1a)
VA=11.30cm^3
CA=5.3g/dm^3
VB=25.0cm^3
CB=Yg/dm^3
HCL(aq)+NaOH(aq)-->NaCl(aq)+H2O(l)

(i)
For acid nA:nB=1:1
Conc. of A in mol/dm^3=Conc of A in g/dm^3/molar mass in g/mol
HCl=1+35.5=36.5g/mol
=5.3/36.5
=0.145mol/dm^3
CAVA/CBVB=nA/nB
(0.145*11.30)/(CB*25.0)=1/1
1.6385=25CB
CB=1.6385/25
CB=0.06554mol/dm^3

(ii)
Conc of B in mol/dm^3=Conc of A in g/dm^3/molar mass in g/mol
0.0655=Yg/dm^3/40
Y=2.62g/dm^3
Molar mass of Y(NaOH)=23+16+1=40g/mol
The value of Y is 2.62g/dm^-3

(iii)
HCl+NaOH-->NaCl+H2O
1 mole of HCl gives 1 mole of NaCl
1.6385 mole of HCl would give 1.6385 mole of NaCl
n=CV
=0.145*11.30
=1.6385mole
No of mole =Mass/Molar mass
1.6385=mass/58.5
Molar mass of NaCl=58.5g/mol
Massof NaCl=58.5*1.6385
=95.85

(1b)
-Methyl orange
-Yellow

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(3a)
Sucrose + Benedict solution+heat => no colour change
Inference: non reducing sugar present.

Glucose+Benedict solution+heat=> brick red colour formed.
Inference: Reducing sugar like glucose present

(3bi)
(i) potassium iodide
(ii) throsulphate

(3bii)
Starch indicator

(3biii)
(i)before end point - dark color
(ii)at the end point -  colourless

(3c)
(i) Soda lime is preferred because it does not attack rubber
(ii) Because soda lime is not deliquescent