JUPEB 2026 Chemistry Practical Examination Qualitative Analysis

 

In this class today, we are going to look at all the possible tests , observations and inferences which you are to be expecting in this year’s JUPEB exams. The compounds you are going to analysis an organic and inorganic compounds. The first one will be tagged C(mixture of ethanol and ethanoic acid in equal portion) while the other will be tagged D(anhydrous CuSO₄ and anhydrous NaCl in equal portion).

 The question below will aim us to actually understand the expected test , observation and inferences.

 Model Question:

 Sample C is a mixture of organic compounds and D is a mixture of inorganic compounds. Carry out the following tests and identify any gas involved.

 

 

S/N	Test	Observation	Inference
a (I)	Add about 5cm3 of  C in test-tube + NaHCO3	Effervescence occurs, colourless, odourless gas liberated, turns lime water milky	C is an organic acid
(II)	To another portion of C, add 2cm3 conc. H2SO4 then boil gently	Sweety smelling solution formed	Easter( alkanoate) confirmed
b (I)	D + distilled water, stir, divide into four portions	Soluble and gives a light blue solution	Mixture soluble compounds, transition ion likely present
(II)	To a portion of D, add dilute NaOH solution in drops then in excess	Blue gelatineous precipitate, insoluble in excess	Cu2+ likely present
(III)	To another portion of D, add aqueous Ammonia in drops then in excess	Pale blue gelatineous precipitate, soluble in excess forms a deep blue solution	Cu2+ present
(IV)	To another portion of D, add potassium hexacyanoferrate (II) solution and ethanoic acid	Redish brown precipitate formed	Cu2+ confirmed
c (I)	To another portion of D, add AgNO3	White precipitate which darkens on exposure to sunlight	Cl- present
(II)	Mixture from above (c II) plus dilute HCl	White precipitate insoluble	Cl-  present
(III)	Another portion of mixture from C (ii), add aqueous ammonia solution	Precipitate dissolves	Cl- confirmed