Please provide the procedure, observations, and conclusion for a test identifying carbon dioxide, and identify common hazard symbols.

Here are the answers to questions 3 and 4:

3. The diagrams below illustrate the steps a student used to test for carbon dioxide gas.

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

• I. Sodium carbonate is placed in a flask, and dilute hydrochloric acid is added to it to initiate a reaction and produce gas.
• II. The gas produced from the reaction in step I is collected and passed through a delivery tube.
• III. The gas from the delivery tube is bubbled through a solution of lime water (calcium hydroxide solution) in a test tube.
• IV. The observation is made that the lime water turns milky or cloudy.

3. b) Give two (2) observations made in the test.

• Effervescence (fizzing or bubbling) is observed when sodium carbonate reacts with dilute hydrochloric acid.
• The lime water (calcium hydroxide solution) turns milky or cloudy.

3. c) Write the conclusion drawn from the test.
The gas produced from the reaction of sodium carbonate and dilute hydrochloric acid is carbon dioxide, as it turned lime water milky.

4. The diagrams below show some hazard symbols usually displayed on chemical containers.

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

• A: Warning / Irritant / Health Hazard
• B: Corrosive
• C: Oxidizer
• D: Toxic / Poison
• E: Explosive

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

• A (Warning / Irritant): Ammonia, Ethanol
• B (Corrosive): Hydrochloric acid, Sodium hydroxide
• C (Oxidizer): Hydrogen peroxide, Potassium permanganate
• D (Toxic): Cyanide, Mercury compounds
• E (Explosive): Nitroglycerin, TNT (Trinitrotoluene)

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

• Keep the chemical away from flammable materials, as oxidizers can cause or intensify fire.
• Store the chemical in a cool, well-ventilated area, separate from combustible substances.