Question 1: Explain what is meant by the term 'halogen' and list the elements that belong to Group 7 of the periodic table.

Answer: Halogens are non-metal elements in Group 7 of the periodic table that are highly reactive and exist as diatomic molecules. The elements are fluorine, chlorine, bromine, iodine, astatine, and tennessine.

Question 2: Describe the trend in reactivity of halogens as you move down Group 7.

Answer: Reactivity decreases as you move down the group because the atomic size increases, making it harder for the atoms to attract electrons during reactions.

Question 1: What is the typical state (solid, liquid, or gas) of each halogen at room temperature?

Answer: Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids.

Question 2: Explain why fluorine is more reactive than iodine.

Answer: Fluorine is more reactive because it has a smaller atomic radius and greater electronegativity, making it more effective at attracting electrons during reactions.

Question 1: Describe the general process of a halogen displacement reaction and give an example.

Answer: A more reactive halogen displaces a less reactive halogen from its compound in solution. For example, chlorine displaces bromine from potassium bromide: Cl₂ + 2KBr → 2KCl + Br₂.

Question 2: Predict whether iodine can displace bromine from potassium bromide solution.

Answer: No

Question 1: Name one common use of chlorine in industry and explain why it is suitable for this purpose.

Answer: Chlorine is used in water treatment to disinfect water because it kills bacteria and other pathogens effectively.

Question 2: Identify two safety precautions that should be taken when handling halogens in the laboratory.

Answer: Wearing protective gloves and goggles, and working in a well-ventilated area or fume cupboard.

Question 1: Calculate the mass of chlorine gas required to react completely with 10 grams of potassium bromide (KBr). The reaction is: Cl₂ + 2KBr → 2KCl + Br₂. (Molar mass of Cl₂ = 70.9 g/mol, KBr = 119 g/mol)

Answer: Moles of KBr = 10 g / 119 g/mol ≈ 0.084 mol; Moles of Cl₂ needed = 0.084 mol; Mass of Cl₂ = 0.084 mol × 70.9 g/mol ≈ 5.96 g.

Question 2: In a reaction, 25 grams of iodine is reacted with excess chlorine. If the reaction produces 15 grams of iodine vapor, what can you infer about the reaction's efficiency?

Answer: The reaction appears inefficient or incomplete, since only 15 g of iodine vapor is produced from 25 g reacted, indicating a possible loss or side reactions.

Question 1: Explain how halogens are used in modern medicine, providing a specific example.

Answer: Halogens like iodine are used in antiseptics and disinfectants; for example, iodine solutions are used to sterilize wounds and surgical instruments.

Question 2: Describe one environmental concern related to the use or disposal of halogens.

Answer: Disposal of halogenated compounds can lead to environmental pollution, such as the formation of persistent organic pollutants or ozone-depleting substances like CFCs.