Question 1: Define Carbon Dioxide (CO₂) and describe its common physical state at room temperature and pressure.

Answer: Carbon Dioxide is a colourless, odourless gas composed of one carbon atom and two oxygen atoms. It is a gas at room temperature and pressure.

Question 2: Explain how Carbon Dioxide can be identified in a laboratory setting using a chemical test.

Answer: Carbon Dioxide can be identified by passing it through limewater, which turns from colourless to cloudy or milky due to the formation of calcium carbonate.

Question 1: Calculate the volume of Carbon Dioxide produced at room temperature and pressure when 5 grams of calcium carbonate (CaCO₃) decomposes completely. (Molar mass of CaCO₃ = 100 g/mol, molar volume of gas at RTP = 24 dm³/mol).

Answer: 144 dm³

Question 2: If 10 dm³ of Carbon Dioxide is collected, how many moles of gas does it contain? (Use molar volume at RTP = 24 dm³/mol).

Answer: 0.417 mol

Question 1: Describe a simple laboratory experiment to test for the presence of Carbon Dioxide using limewater. Include the key variables and safety precautions.

Answer: Set up a test tube with a source of Carbon Dioxide, such as from the reaction of hydrochloric acid with marble chips. Pass the gas through limewater in a test tube or trough; if the limewater turns milky, Carbon Dioxide is present. Key variables include the amount of reactants, gas flow rate, and limewater volume. Safety precautions involve handling acids carefully and wearing safety goggles.

Question 1: A student collects 12 dm³ of a gas and tests it with limewater, which turns cloudy. What does this indicate about the gas? Explain your reasoning.

Answer: The gas is Carbon Dioxide because it reacts with limewater to produce a milky precipitate of calcium carbonate, indicating the presence of CO₂.

Question 1: Describe the chemical reaction involved when Carbon Dioxide turns limewater milky. Include the chemical equation and explain the significance of this test in identifying Carbon Dioxide.

Answer: Carbon Dioxide reacts with calcium hydroxide in limewater to form calcium carbonate, which appears as a milky precipitate. The chemical equation is: Ca(OH)₂ + CO₂ → CaCO₃ (s) + H₂O. This test is significant because it provides a visible indication of CO₂ presence in a gas sample.

Question 1: Explain how Carbon Dioxide is used in industry for carbonating soft drinks and the safety considerations involved in this process.

Answer: Carbon Dioxide is dissolved under pressure in soft drinks to produce carbonation, giving the drinks their fizz. Safety considerations include handling high-pressure equipment carefully and ensuring proper ventilation to prevent CO₂ build-up, which can cause suffocation.