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NECO Chemistry Practical Specimen 2021
These are the recent 2021 NECO Chemistry Specimen;
NECO Chemistry Practical Questions and Answers (Updated)
Note that the above are the practical Specimen for NECO Chemistry Practical and not answers to any questions. Here is the answers while the exams will comense.
2021 NECO Chemistry Answers Updated
(1a)
Tabulate
Volume of pipette used=25cm3.
Indicator used= Methyl orange
Under Titration, Rough, 1st, 2nd, 3rd,
Final burette reading; |25.00| |23.40| |23.50| 23.60|
Average volume of Acid used=23.40+23.50+23.60/3 =70.5/3=23.50cm3
(1aii)
This is because it is a reaction between a weak acid and strong base
(1aiii)
A funnel should be used while transferring the acid into the burette.
(1bi)
Conc of A in mol|dm³ =?
Conc of A in g|dm³ = 12.75g|dm³
Molar mass of A, NaHSO⁴ = 23+1+32+64
=120g|dm³
From.
Conc(mol/dm³) = conc(g/dm³)/molar mass
Conc =12.75/120
Conc =0.106mol/dm³
(1bii)
Con of B in mol/dm³ =?
Ca =0.106, Cb =? Va =23.50cm³, Vb =25.00cm³
na=1 , nb=1
From; CaVa/CbVb=na/nb
Cb=CaVanb/Vbna
Cb=0.10623501/25.001
Cb=2.5/25
Cb=0.1mol/dm³
(1biii)
Conc of B in g/dm³=?
Molar mass of B , NaOH=23+16+1=40g/mol
From; conc(g/dm³)=conc(mol/dm³)molar mass
=0.140
=4.0g/dm³
(1biv)
Mass of salt formed =?
Recall mole of NaHSO⁴=?
From; mole =con(mol/dm³)*vol(cm³)/1000
Mole=0.106*23.50/1000
Mole=0.0025mol of NaHSO⁴
By proportion 1mol of NaHSO⁴ produce 1mol of Na²SO⁴ 0.0025mol of NaHSO⁴ will produce X mol of Na²SO⁴ X=0.00251=0.0025mol of NaSO⁴
Molar mass of Na²SO⁴=(232) + 32 + (16*4)
=46+32+64
=142g/mol
Recall; mole =mole/molar mass
Mass =mole * molar mass
Mass =0.0025*142
Mass =0.36g of Na²SO⁴
===========================
(2a)
[PLEASE PUT IN A TABULAR FORM]
TEST
C + 5cm³ of distilled water
OBSERVATION
It dissolve completely
INTERFERENCE
C is a soluble salt
(2bi)
TEST
Solution + NaOH + Heat
OBSERVATION
Effervescence occurs in which a colourless gas with pungent smell and turns red litmus paper to blue is given off.
INFERENCES
NH³ gas from NH⁴+ is present
(2bii)
TEST
Stirring rod of HCL + gas given off
OBSERVATION
a gas which gives a pop sound is given off
INFERENCES
H² is present
(2ci)
TEST
Solution C + drops of BaCL²
OBSERVATION
a white precipitate is formed
INFERENCES
CO²^-3, SO²^-4, SO²^-3, May be present.
(2cii)
TEST
Solution in C(i) + dil HCL
OBSERVATION
the white precipitate dissolve is dil HCL and effervescence occurs in which a colourless and odourless gas which turns blue litmus red and lime water milky is given off
