Question 1: Define a halide ion and give three examples of halide ions commonly tested in the laboratory.

Answer: A halide ion is a negatively charged ion derived from a halogen element (fluorine, chlorine, bromine, iodine, astatine). Examples include chloride (Cl−), bromide (Br−), and iodide (I−).

Question 2: Explain the principle behind using silver nitrate solution to identify halide ions.

Answer: Silver nitrate reacts with halide ions to form insoluble silver halide precipitates. The different halides produce distinct precipitates: chloride (white), bromide (cream), and iodide (yellow), allowing identification based on color and solubility.

Question 1: Describe the steps involved in testing a sample for chloride ions using silver nitrate solution.

Answer: First, place a small amount of the sample solution in a test tube. Add a few drops of dilute nitric acid to remove any interfering ions. Then, add a few drops of silver nitrate solution. Observe the formation of a white precipitate, which indicates the presence of chloride ions.

Question 2: Identify two variables that should be controlled during halide testing and explain why.

Answer: Variables include the concentration of the sample solution and the amount of silver nitrate added. Controlling these ensures consistent and accurate results, preventing false positives or negatives.

Question 3: List two safety precautions that should be taken when handling silver nitrate and acids during halide tests.

Answer: Wear safety goggles and gloves to protect skin and eyes from silver nitrate and acids. Work in a well-ventilated area to avoid inhaling fumes.

Question 1: A student tests three different solutions and observes the formation of precipitates with silver nitrate. Solution A produces a white precipitate, Solution B produces a cream precipitate, and Solution C produces a yellow precipitate. Identify the halide ions in each solution.

Answer: Solution A contains chloride ions, Solution B contains bromide ions, and Solution C contains iodide ions.

Question 2: Explain why adding dilute nitric acid before silver nitrate is important in halide testing.

Answer: Adding dilute nitric acid removes carbonate and other interfering ions that could produce false precipitates, ensuring that the test accurately detects halide ions.

Question 1: Calculate the amount of silver nitrate (in grams) needed to completely react with 0.05 mol of chloride ions. (Atomic mass of AgNO3 = 169.87 g/mol)

Answer: 8.49 grams

Question 2: Discuss how the identification of halide ions can be useful in the food industry.

Answer: The food industry uses halide tests to determine the presence of certain additives or contaminants, such as iodine in salt or bromides in preserved foods, ensuring safety and compliance with regulations. Additionally, halide analysis helps in quality control and verifying the purity of products.

Question 3: Which halide ion would produce a yellow precipitate with silver nitrate?

Answer: Iodide