Question 1: Define a carbonate ion and give its chemical formula.

Answer: A carbonate ion is a polyatomic ion with the formula CO₃²⁻, consisting of one carbon atom bonded to three oxygen atoms arranged in a trigonal planar structure.

Question 2: Describe the typical chemical reaction when a carbonate sample reacts with dilute hydrochloric acid.

Answer: The carbonate reacts with dilute hydrochloric acid to produce carbon dioxide gas, water, and a salt. The reaction is: CO₃²⁻ + 2H⁺ → CO₂ + H₂O.

Question 3: Explain why carbon dioxide gas is produced during the test for carbonate ions.

Answer: Carbon dioxide is produced because the carbonate ions react with acids to release CO₂ gas as a decomposition product.

Question 1: Outline the essential safety precautions to take when performing a carbonate test with hydrochloric acid.

Answer: Wear safety goggles and gloves to protect against acid splashes, work in a well-ventilated area, and handle acids with care to prevent spills and skin contact.

Question 2: Identify the independent variable, dependent variable, and control in a typical carbonate test experiment.

Answer: Independent variable: Concentration of acid; Dependent variable: Volume of carbon dioxide produced; Control: Type and amount of carbonate sample.

Question 3: Describe a step-by-step procedure to test whether a sample contains carbonate ions.

Answer: First, place a small amount of the sample in a test tube. Add a few drops of dilute hydrochloric acid. Observe for effervescence indicating carbon dioxide release. Confirm the presence of CO₂ by bubbling the gas through limewater; if the limewater turns milky, the sample contains carbonate ions.

Question 1: A student reacts 2.0 g of a carbonate sample with excess dilute hydrochloric acid. The volume of CO₂ produced at room temperature and pressure is 24.0 cm³. Calculate the molar amount of CO₂ released. (Molar volume of gas at room temperature and pressure = 24 dm³/mol)

Answer: Number of moles of CO₂ = Volume of CO₂ / Molar volume = (24.0 cm³ / 1000) / 24 dm³/mol = 0.001 mol.

Question 2: Based on the data above, what is the molar mass of the carbonate sample? Show your working.

Answer: Molar mass = mass / moles = 2.0 g / 0.001 mol = 2000 g/mol. (Note: This indicates an unusually large molecular weight; in practical cases, re-evaluate the data or sample.)

Question 3: Interpret why the volume of CO₂ produced is important in analysing the purity of a carbonate sample.

Answer: The volume of CO₂ indicates the amount of reactive carbonate present; deviations from expected volumes can suggest impurities or incomplete reactions.

Question 1: Explain how the detection of carbonate ions is utilised in the construction industry.

Answer: Carbonate detection helps assess the purity of limestone and other carbonate-containing materials used in cement and building products, ensuring structural integrity and quality.

Question 2: Describe a modern technological application that involves the analysis of carbonate ions.

Answer: In environmental monitoring, carbonate analysis is used to assess water alkalinity and buffering capacity, which is crucial for maintaining aquatic ecosystem health.