Page 90 - Chemistry_Form_2

Chemistry
for Secondary Schools

Activity 4.1

Aim: To verify the law of conservation of matter (mass) and precipitation
reaction
FOR ONLINE READING ONLY
Requirements: Conical flasks, analytical balance, 100-mL measuring cylinders,
1 M barium chloride solution, and 1 M zinc sulfate solution

Procedure
1. Weigh the mass of two empty conical flasks and record the results.
2. Put about 50 cm of 1 M barium chloride solution in one of the flasks and
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another 50 cm of 1 M zinc sulfate in the second flask.
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3. Weigh the flasks to get the mass of their solutions and flasks and record
the results.
4. Pour the weighed solution of barium chloride into a flask containing zinc
sulfate. Swirl the mixture.

5. Weigh the mixture after the reaction and record the results.

Questions

1. What is the total mass of the solutions before the reaction?
2. What is the mass of the mixture after the reaction?
3. What is the colour of the mixture after the reaction?
4. Write the balanced chemical equation for the reaction.

Ionic equations

An ionic equation is a chemical equation in which compounds in aqueous solutions
or in molten state are written as dissociated ions. Ionic equations are commonly
used in displacement reactions in aqueous solutions. In these equations, spectator
ions are omitted to give a net ionic equation. Spectator ions are the ions that do
not change their valence states in the reaction since they remain unchanged in a

chemical reaction.

The following steps are followed when writing an ionic equation:
1. Write the balanced chemical equation in symbols; ensure all formulas are correct.

2. Split all soluble ionic compounds into individual ions to get the total ionic
equation.

Student’s Book Form Two 83

01/08/2025 11:20:58
CHEMISTRY FORM TWO NEW 2025 DUMMY.indd 83 01/08/2025 11:20:58
CHEMISTRY FORM TWO NEW 2025 DUMMY.indd 83