2026 WAEC CHEMISTRY PRACTICAL TUTORIAL

This tutorial class will be useful to you if you are preparing for WAEC  chemistry practical examination. It can also be relevant for candidates preparing any other chemistry practical examination.

  Today’s class will based on salt analysis or quantitative analysis. We are going to analyse a mixture of copper tetraoxosulphate (VI) and glucose. We will show you how to identify the ions in copper teteraoxosulphate (VI) and glucose in table below :

Question  and  answer

C is a mixture of two compounds, one organic and the other inorganic. Carry out the follow test below and record your observation and inference

 

S/n	Test	Observation	Inference
a.	C + distilled water and stir gently. Divide into four portions		C is soluble and transition ions likely present.
b.	To the first portion from (a) above, add dilute NaOH in drops then excess.	Pale or light blue gelatinous precipitate insoluble in excess
c.	To the second portion from above (a), add aqueous ammonia solution in drops then excess		Cu2+ confirmed
d.	To the third portion from above (a), add BaCl2 solution	White precipitate formed
e.	To the mixture from (d) + dilute HCl		SO42- confirmed
f.	To the fourth portion form above (a), add fehling’s solution A and B in 1:1 ratio and heat gently	Brick-red coloured precipitate formed

 

 Answers:

 

S/n	Test	Observation	Inference
a.	C + distilled water and stir gently. Divide into four portions	Soluble and gives blue solution	C is soluble and transition ions likely present.
b.	To the first portion from (a) above, add dilute NaOH in drops then excess.	Pale or light blue gelatinous precipitate insoluble in excess	Cu2+ likely present
c.	To the second portion from above (a), add aqueous ammonia solution in drops then excess	Pale blue gelatinous precipitate soluble in excess and gives a deep blue solution	Cu2+ confirmed
d.	To the third portion from above (a), add BaCl2 solution	White precipitate formed	SO32-, CO32-, SO42- likely present
e.	To the mixture from (d) + dilute HCl	Precipitate insoluble	SO42- confirmed
f.	To the fourth portion form above (a), add fehling’s solution A and B in 1:1 ratio and heat gently	Brick-red coloured precipitate formed	Glucose or reducing sugar confirmed

 

Note:  SO₃^2-, CO₃^2-, SO₄^2-  produce white precipitate with barium chloride but only SO₄^2- is insoluble in dilute HCl