Question 1: Explain the chemical principle behind the test for carbonate ions using dilute acid.

Answer: Carbonate ions react with dilute acid to produce carbon dioxide gas, which can be detected by its effervescence and can be tested by passing the gas through limewater, which turns milky.

Question 1: Define a carbonate ion and give an example of a common carbonate compound.

Answer: A carbonate ion is a polyatomic ion with the formula CO₃²⁻; an example is calcium carbonate (CaCO₃).

Question 2: Describe the mechanism by which dilute hydrochloric acid reacts with a carbonate.

Answer: The acid reacts with the carbonate to produce carbon dioxide gas, water, and a salt. The reaction involves the carbonate ion reacting with hydrogen ions from the acid, releasing CO₂.

Question 1: Design a simple experiment to test whether a given sample contains carbonate ions. Include the key variables and safety precautions.

Answer: To test for carbonate ions, add dilute hydrochloric acid to the sample and observe for effervescence indicating CO₂ production. Variables include the amount of acid and sample size. Safety precautions include wearing goggles and gloves to handle acids, and conducting the test in a well-ventilated area.

Question 1: A student reacts 5.0 g of a mineral sample with excess dilute acid and collects 0.12 L of carbon dioxide gas at room temperature and pressure. Calculate the molar amount of carbonate in the sample. (Molar volume of gas at room temperature = 24 dm³/mol)

Answer: Number of moles = Volume of CO₂ / Molar volume = 0.12 dm³ / 24 dm³/mol = 0.005 mol. Therefore, the sample contains 0.005 mol of carbonate ions.

Question 1: Describe the steps and safety precautions involved in testing a mineral sample for carbonate ions in a practical setting. (6 marks)

Answer: First, wear appropriate safety gear including goggles and gloves. Place a small amount of the mineral sample in a test tube. Add dilute hydrochloric acid carefully and observe for effervescence. Confirm CO₂ production by passing the gas through limewater, which should turn milky. Ensure good ventilation and handle acids with care to avoid spills and inhalation hazards.

Question 1: Explain how the carbonate test is used in the industry for quality control in the manufacture of cement.

Answer: The carbonate test helps determine the amount of carbonate present in raw materials like limestone. Proper carbonate levels are essential for the chemical reactions during cement production, ensuring consistent quality and strength.