Tagged: NECO EXPO
July 15, 2021 at 6:24 am #392709Godwin EmmanuelKeymaster
2021 NECO CHEMISTRY PRACTICAL ANSWER
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|
Initial burette reading; |0.00| |0.00| |0.00| |0.00|
Volume of A used; |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
This is because it is a reaction between a weak acid and strong base
A funnel should be used while transferring the acid into the burette.
Conc of A in mol|dm³ =?
Conc of A in g|dm³ = 12.75g|dm³
Molar mass of A, NaHSO⁴ = 23+1+32+64
Conc(mol/dm³) = conc(g/dm³)/molar mass
Con of B in mol/dm³ =?
Ca =0.106, Cb =? Va =23.50cm³, Vb =25.00cm³
na=1 , nb=1
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
Mass of salt formed =?
Recall mole of NaHSO⁴=?
From; mole =con(mol/dm³)*vol(cm³)/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)
Recall; mole =mole/molar mass
Mass =mole * molar mass
Mass =0.36g of Na²SO⁴
[PLEASE PUT IN A TABULAR FORM]
C + 5cm³ of distilled water
It dissolve completely
C is a soluble salt
Solution + NaOH + Heat
Effervescence occurs in which a colourless gas with pungent smell and turns red litmus paper to blue is given off.
NH³ gas from NH⁴+ is present
Stirring rod of HCL + gas given off
a gas which gives a pop sound is given off
H² is present
Solution C + drops of BaCL²
a white precipitate is formed
CO²^-3, SO²^-4, SO²^-3, May be present.
Solution in C(i) + dil HCL
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
CO² gas from CO²^3- confirmed
concentrated acid can be defined as an acid formed when a large quantity of an acid dissolve in a small or little volume of water.
A strong acid is defined as a type of acid that ionize completely in a solution
Activated charcoal is used as an adsorbent material
(i)Reddish – Brown
(ii) I – red, II – brown.
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