Question 1: Define chlorine in terms of its chemical properties and common uses.

Answer: Chlorine is a yellow-green gas with a pungent smell, used for disinfecting water, in the production of plastics like PVC, and as a bleaching agent.

Question 2: Describe the typical physical state and color of chlorine gas at room temperature.

Answer: Chlorine gas is a yellow-green, diatomic gas at room temperature.

Question 3: Explain the mechanism by which chlorine reacts with sodium bromide in a solution.

Answer: Chlorine oxidizes bromide ions (Br-) to bromine (Br2), while chlorine itself is reduced to chloride ions (Cl-).

Question 1: Describe a safe method to test for the presence of chlorine gas in a laboratory setting.

Answer: Expose a damp litmus paper to the gas; if chlorine is present, the paper turns white due to bleaching.

Question 2: List two safety precautions that should be taken when working with chlorine gas.

Answer: Use a fume hood to avoid inhalation and wear appropriate protective clothing and gloves.

Question 3: Identify the variables that need to be controlled in an experiment testing the reaction of chlorine with different metal powders.

Answer: Temperature, concentration of chlorine, amount of metal powder, and reaction time.

Question 1: A sample of chlorine gas reacts with potassium iodide solution, turning the solution brown due to iodine formation. Explain the chemical process involved.

Answer: Chlorine oxidizes iodide ions (I-) to iodine (I2), which then dissolves in the solution, giving it a brown color. The reaction is Cl2 + 2I- → 2Cl- + I2.

Question 1: Calculate the volume of chlorine gas (at STP) required to react completely with 0.5 mol of sodium bromide (NaBr). Use the reaction: Cl2 + 2NaBr → 2NaCl + Br2.

Answer: According to the reaction, 1 mol of Cl2 reacts with 2 mol of NaBr. Therefore, 0.5 mol NaBr requires 0.25 mol Cl2. Using molar volume at STP (22.4 L/mol), volume = 0.25 mol × 22.4 L/mol = 5.6 liters.

Question 1: Explain how chlorine is used in water treatment plants to disinfect drinking water.

Answer: Chlorine is added to water to kill bacteria and other pathogens, making it safe for drinking. It reacts with organic matter and microbes, destroying their cell walls.

Question 2: Discuss one environmental concern associated with the use of chlorine.

Answer: Chlorine can form harmful chlorinated compounds like dioxins and trihalomethanes, which are toxic and may contaminate water sources.