Question 1: What is the definition of Relative Formula Mass (Mr)?

Answer: Relative Formula Mass (Mr) is the sum of the atomic masses of all atoms in a chemical formula, relative to 1/12th the mass of a carbon-12 atom.

Question 2: Why is Relative Formula Mass useful in chemistry?

Answer: It helps chemists calculate the amounts of substances involved in reactions, enabling precise measurements and stoichiometric calculations.

Question 1: Calculate the Relative Formula Mass of water (H₂O). Atomic masses: H = 1, O = 16.

Answer: 18

Question 2: Determine the Mr of carbon dioxide (CO₂). Atomic masses: C = 12, O = 16.

Answer: 44

Question 3: What is the Mr of sodium chloride (NaCl)? Atomic masses: Na = 23, Cl = 35.5.

Answer: 58.5

Question 1: Describe a simple experiment to determine the mass of a solid sample of a compound. Include safety precautions.

Answer: Students should use a balance to measure the mass of the solid while ensuring the balance is calibrated. Safety precautions include wearing safety goggles, handling chemicals with care, and avoiding inhalation or contact with harmful substances.

Question 2: Identify at least two variables that need to be controlled in an experiment measuring the mass of a chemical compound.

Answer: Temperature and humidity should be controlled, and the instrument calibration checked to ensure accuracy.

Question 1: A sample contains 12 grams of carbon and 16 grams of oxygen. Using atomic masses (C=12, O=16), determine the empirical formula and its Mr.

Answer: Moles of C = 12/12=1, Moles of O=16/16=1. Empirical formula is CO. Mr of CO = 12+16=28.

Question 1: Explain how understanding the Mr of a drug compound is important in pharmaceutical manufacturing.

Answer: Knowing the Mr ensures accurate dosing, proper formulation, and consistency in drug production, which is vital for safety and efficacy.

Question 2: Describe a scenario in industry where calculating the Mr of a chemical is crucial for environmental safety.

Answer: In waste treatment, determining the Mr of pollutants helps in assessing the amount of chemicals needed for neutralization or removal, preventing environmental contamination.