Home WAEC NECO NABTEB
JAMB CBT JUPEB IJMB Other Exams Main Website
Want To Contact Us? Click Here

Quick Contact

Click To Send Us SMS Now
Click To Chat Examrelief On WhatsApp

Latest WAEC on Giditrends

WAEC 2018 Chemistry Practical Alternative B Questions and Answers
WAEC April 21, 2018 • 3 years ago • No Comment Yet

WAEC 2018 Chemistry Practical Alternative B Questions and Answers, WAEC 2018 Chemistry Practical Alternative B Expo, WAEC 2018 Chemistry Practical Alternative B Runs, WAEC 2018 Chemistry Practical Alternative B Choke, WAEC 2018 Chemistry Practical Alternative B Dubs, WAEC 2018 Chemistry Practical Alternative B Link, WAEC 2018 Chemistry Practical Questions and Answers, WAEC 2018 Chemistry Practical Expo, WAEC 2018 Chemistry Practical Runs, WAEC 2018 Chemistry Practical Choke, WAEC 2018 Chemistry Practical Dubs, WAEC 2018 Chemistry Practical Link
WAEC 2018 CHEMISTRY PRACTICAL ALTERNATIVE B QUESTIONS AND ANSWERS

100% VERIFIED CHEMISTRY PRACTICAL ANSWERS
B)
i)
Concentration of A in mol dm-3
From the reaction equation
CA VA = 1
CB VB 2
CA = CB VB
2 VA
CA = 0.0975 x 25
2 VA
= P mol dm-3
Alternative Method:
Amount of acid used = 0.025 x 0.0975 = 0.00244 mol
From the equation of reaction:
2 mol of B require 1 mol of A
0.00244 mol of B requires ½ x 0.00244 mol of A
= 0.00122 mol of A.
i.e VA cm3 contain 0.00122 mol.
1000 cm3 contain 0.00122 x 1000/VA mol.
i.e. Conc of A = 1.22/VA = P mol dm-3
(ii)
Molar mass of H2Y
Molar mass of H2Y = 6.22
P
= Q g mol-1
=================================
3i).
Using BENEDICT’S REAGENT.
Step 1
Turn on your gas to medium heat and place your beaker filled with 100 mL of water on it. Bring it to a boil.
Step 2
crush the solid sample into a powder using a mortar and pestle. Add water to the powder and pour it in the test tube.
Step 3
Add approximately 1 mL of Benedict’s solution to the test tube using a dropper. Slowly swirl the test tube counterclockwise to distribute the reagent evenly.
Step 4
Place your test tube into the beaker until you note a color change — this process usually takes five minutes.
Step 5
Examine the color change, if it is present. Benedict’s reagent has a color change gradient from blue, meaning no simple sugars are present, to green, yellow, orange, red and brown. The color sequence indicates the increasing concentration of the simple sugar, with green being the lowest and brown being the highest.

Click Here To Comment

Leave a Reply