A student performed a test to identify a gas by reacting sodium carbonate with dilute hydrochloric acid. Describe the procedure, list observations, state the conclusion, and identify hazard symbols an

Here are the answers to the questions:

3.

a) Write out the procedure used by the student in each of the steps:

• I: Sodium carbonate is reacted with dilute hydrochloric acid in a conical flask to produce a gas.
• II: The gas produced is passed through a delivery tube into an intermediate test tube for transfer.
• III: The gas is then bubbled through lime water (calcium hydroxide solution) in a test tube.
• IV: The lime water turns milky, indicating the presence of carbon dioxide.

b) Give two (2) observations made in the test:

1. Effervescence (bubbling/fizzing) is observed in the conical flask in Step I.
2. The lime water turns milky/cloudy in Step IV.

c) Write the conclusion drawn from the test:
The gas produced is confirmed to be carbon dioxide.

4.

a) Identify each of the symbols labelled A, B, C, D and E:

• A: Irritant / General Hazard
• B: Corrosive
• C: Flammable
• D: Toxic / Poisonous
• E: Environmental Hazard

b) Name two (2) chemicals which can be associated with each symbol A, B, C, D and E:

• A (Irritant): Ammonia, Bleach (dilute)
• B (Corrosive): Concentrated hydrochloric acid, Sodium hydroxide
• C (Flammable): Ethanol, Petrol
• D (Toxic): Cyanide, Mercury compounds
• E (Environmental Hazard): Pesticides, Heavy metal compounds

c) State two (2) safety precautions that should be taken when handling chemicals with symbol C:

1. Keep the chemical away from open flames, sparks, and heat sources.
2. Ensure adequate ventilation to prevent the accumulation of flammable vapours.