2023-WAEC-CHEMISTRY-PRACTICALS-ANSWERS!l
(1)

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

(2)
(2a)
TEST; C + distilled water + shake

OBSERVATIONS; It dissolves to give a colourless or clear solution

INFERENCE; Soluble salt suspected

(2ai)
TEST; Solution C + litmus paper

OBSERVATIONS; It has no effect on both blue and red litmus paper

INFERENCE; Neutral solution

(2aii)
TEST; solution C + Fehling solution A and B + heat

OBSERVATIONS; It gives a black red colour

INFERENCE; Reading agent confirmed

(2bi)
TEST; D + heat

OBSERVATIONS; It turns yellow on heating and white on cooling

INFERENCE; ZnO is present

(2bii)
TEST; D + dilute Hcl + heat

OBSERVATIONS; It dissolves completely to give a clear or colourless solution

INFERENCE; Solution chlorides of Zn³+, Al³+ is present

(2biii)
TEST; Solution D + NaOH in drops and then in excess

OBSERVATIONS; It gives white gelatinous precipitate. The precipitate is soluble in excess.

INFERENCE; Al³+, Zn²+ present.
Al³+, Zn²+ present .

(2biv)
TEST; Solution D + NH3 in drops and then in excess

OBSERVATIONS; It gives white gelatinous precipitate. The precipitate is soluble in excess NH3

INFERENCE; Al³+, Zn²+ is present.
Zn²+ confirmed.

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

(3b)
– Obtain a small amount of benzoic acid
– Prepare a melting point apparatus
– Fill the capillary tube with the sample of benzoic acid powder
– Insert the capillary tube unit the melting point apparatus
– Begin heating the temperature is increased at a slow rate you allow pressure observation of the melting point
– Observe the melting point
– Repeat the process to ensure accuracy
– Record the melting point

(3)

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

Completed!.