Page 117 - Chemistry_Form_2

Chemistry
for Secondary Schools

Weak bases are those bases which do not completely dissociate into their ions
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in aqueous solutions. The most common example of a weak base is ammonium
hydroxide.

Acidity of a base

The acidity of a base is the number of hydroxide ions that a basic molecule can
produce in the aqueous solution. On the basis of acidity, bases are classified into
three types: monoacidic, diacidic, and triacidic bases. Table 5.4 shows some of
the bases with their acidity.

Table 5.4: Acidity of some bases
Base Acidity

Monoacidic
Diacidic
Triacidic

Activity 5.2

Aim: To identify acidic and basic substances
Requirements: Coconut, citrus fruits, ripe tomatoes, vinegar, sour milk, wood
ash, pieces of chalk, yoghurt, blender, knife, water, red litmus
papers, blue litmus papers, and beakers

Procedure
1. Prepare juices of coconut, citrus fruits, and ripe tomatoes.
2. Use litmus papers to test the acidity or basic nature of the juices obtained in
Step 1.
3. Mix some wood ash and chalk powder, each with little water, decant to
obtain a supernatant and use litmus papers to test the acidity or basic nature
of the supernatant.

4. Take small amounts of vinegar, sour milk, and yoghurt into separate beakers
and test for acidity or basic nature using litmus papers.

110 Student’s Book Form Two

01/08/2025 11:21:04
CHEMISTRY FORM TWO NEW 2025 DUMMY.indd 110
CHEMISTRY FORM TWO NEW 2025 DUMMY.indd 110 01/08/2025 11:21:04