Question 1: Define the term 'halogen' and list the elements that belong to Group 7 of the periodic table.

Answer: A halogen is a non-metal element found in Group 7 of the periodic table, which includes fluorine, chlorine, bromine, iodine, and astatine.

Question 2: Explain why halogens are considered to be reactive non-metals.

Answer: Halogens are highly reactive because they have seven electrons in their outer shell and readily gain one electron to achieve a full outer shell, forming negative ions.

Question 1: Describe the trend in reactivity of the halogens as you move down Group 7.

Answer: Reactivity decreases as you move down Group 7 because the atomic size increases, making it harder for the halogen to attract electrons and participate in reactions.

Question 2: Predict whether chlorine will displace bromine from a solution of potassium bromide. Justify your answer.

Answer: Yes, chlorine will displace bromine because chlorine is more reactive than bromine and can oxidise bromide ions to bromine.

Question 3: Write a word equation for the reaction when chlorine displaces iodine from potassium iodide solution.

Answer: Chlorine + potassium iodide → potassium chloride + iodine

Question 1: Describe a safe method for testing the reactivity of halogens using displacement reactions in the laboratory.

Answer: Use dilute solutions of halogen halides in a well-ventilated area, wear appropriate PPE, and add a halogen solution to a solution of a less reactive halogen's salt in a test tube. Observe colour changes. Handle all chemicals with care, avoiding contact and inhalation.

Question 2: Identify the variables that must be controlled during a displacement reaction experiment involving halogens.

Answer: Variables include concentration of solutions, temperature, and the type of halogen salts used to ensure consistent and reliable results.

Question 1: A series of solutions containing potassium halides are tested with chlorine, bromine, and iodine. The results show that chlorine displaces iodine and bromine, bromine displaces iodine, but iodine does not displace any other halogen. Explain these observations.

Answer: These observations reflect the reactivity series of halogens, where chlorine is more reactive than bromine and iodine, and bromine is more reactive than iodine. Iodine is the least reactive and cannot displace any other halogen.

Question 1: Describe one industrial use of chlorine and explain why it is suitable for this purpose.

Answer: Chlorine is used to disinfect drinking water because it kills bacteria and other pathogens effectively, making water safe for consumption.

Question 2: Explain the role of halogens in the production of certain pharmaceuticals or compounds used in everyday products.

Answer: Halogens are used in the synthesis of pharmaceuticals and disinfectants because they can introduce reactive halogen atoms into organic molecules, enhancing their biological activity or antimicrobial properties.

Question 1: Calculate the amount of chlorine gas required to react completely with 0.5 mol of potassium bromide in a displacement reaction. (Use the reaction: Cl₂ + 2KBr → 2KCl + Br₂)

Answer: 0.25 mol of Cl₂ gas is required.

Question 2: If 10.0 g of bromine (molar mass 159.8 g/mol) is produced in a reaction, how many moles of iodine reacted, assuming iodine was the limiting reagent?

Answer: Approximately 0.0625 mol of iodine reacted.