NABTEB GCE Chemistry Practical Questions and Answers – 2019 NABTEB GCE Expo

National Examination Council, NABTEB GCE Chemistry Practical Questions and Answers for 2019 NABTEB GCE Examination is now available, subscribe now and get the questions and already solved answers by Examrelief.
 NABTEB GCE Chemistry Practical Questions and Answers

ATTENTION:- KINDLY NOTE THAT OUR SUBSCRIBERS GET ANSWERS A DAY BEFORE EACH PAPER, ALWAYS SUBSCRIBE TO GET YOUR ANSWERS EARLIER.

👑 2019 NABTEB GCE CHEMISTRY PRACTICAL ANSWERS👑

100% VERIFIED CHEMISTRY PRACTICAL ANSWERS

(1ai)
Concentration of K₂CO₃ in gdm⁻³ =13.8/1 = 13.8gdm⁻³
Molar mas of K₂CO₃ = (39 x 2) + 12 (16×3) = 138gmol⁻¹
Therefore Concentration of K₂CO₃ in mold⁻³ = concentration of K₂CO₃ in gdm⁻³/molar mass of K₂CO₃
= 13. 8/18.8
= 0.100moldm⁻³

(1aii)
HCL(aq) + K₂CO₃(aq) –> KCL(aq) + H₂O(l) + CO₂(g)

(1aiii)
Using CAVA/CBVB = nA/nB
CA = 0.250mold⁻³
CB = 0.100mold⁻³
VA = ?
VB = 25.0cm³
nA = 2 nB = 1
0.250 x VA/0.100 x 25 = 2/1
VA = 0.100 x 25 x 2/0.250 x 1
= 5/0.25
= 20.0cm³

(1aiv)
1 mole of K₂CO₃ —> 1 mole of C0₂
Mole of K₂CO₃ = 0.100 x 25/1000 = 0.0025mold
Therefore 0.0025 moles of K₂CO₃ —> 0.0025moles of C0₂
Volume of C0₂ at S.T.P = 0.0025 x 22.4dm³
= 0.056dm³
= 56cm³ s.t.p

(1b)
(i) it is rinsed with distilled water to make the burrette clean and it is rinsed with the acid in order not to decrease the concentration
(ii) This is to prevent air aspiration
=======================

(2ai)
An orange colour of K₂Cr₂ 0₄ is observed

(2aii)
PLOT THE GRAPH [https://i.imgur.com/JVKGcvM.jpg]

-Graph of height of the product against Volume of K₂Cr₂ 0₄

-Scale 1cm rep 1 unit on both axis

(2aiii)
(I) volume of HCL = 8.0cm³; Amount = 0.500 x 8/1000 = 0.004 mole

(II) volume of K₂Cr₂ 0₄ = 8.0cm³ ; Amount = 0.500 x 8/1000 = 0.004mole
Hence, mole ratio of HCL to K₂Cr₂ 0₄ = 0.004/0.004 = 1/1 = 1:1

(2aiv)
BaCL₂ + K₂Cr₂ 0₄ —> BaCr0₄(g) + 2KCL

(2bi)
(i) Add aqueous potassium iodine (KI) to the solution
(ii) A bright yellow precipitate indicates he presence of pb²

(2bii)
DRAW THE DIAGRAM [CLICK HERE]

====================

(3ai)
Dessicator

(3aii)
Grease should be applied on the lid of the desiccator to make it air tight

(3aiii)
(i) Silica gel
(ii) Fuse calcium chloride
(iii) Calcium oxide

(3b)
DELIQUESCENCE absorb moisture from the atmosphere and then turns into solution while HYGROSCOPY absorb moisture from the atmosphere but does not form solution

(3c)
P –> Sulphur
Q –> Sulphur(iv) oxide
R –> Vanadium oxide
S –> Sulphur(vi) oxide

======COMPLETED=======

Don’t Just Copy Alone, Drop your Comments, Share with your friends on Facebook & Twitter Using the below share buttons and like our Facebook fan pages Here
BEST OF LUCK

We Update Our Social Media Platform With Latest Updates, Don’t Miss Out Join US On Facebook and For Latest Updates.

2 Comments

Leave a Reply

Your Phone Number will not be published.




This site uses Akismet to reduce spam. Learn how your comment data is processed.