Question 1: Explain what is meant by the term 'Relative Formula Mass' (Mr) in chemistry.

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

Question 1: Why is the atomic mass of an element important when calculating its Relative Formula Mass?

Answer: Because the atomic mass indicates the mass of each atom, which is used to sum up the total mass in a compound's formula.

Question 2: Define the term 'mole' and explain its relationship with Relative Formula Mass.

Answer: A mole is a unit that measures the amount of substance, containing Avogadro's number of particles. The mass of one mole of a substance in grams equals its Relative Formula Mass.

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

Answer: Mr = (2 × 1) + 16 = 18

Question 2: Determine the Mr of sodium chloride (NaCl). Atomic masses: Na = 23, Cl = 35.5.

Answer: Mr = 23 + 35.5 = 58.5

Question 3: What is the mass in grams of 2 moles of calcium carbonate (CaCO₃)? Atomic masses: Ca = 40, C = 12, O = 16.

Answer: Mr of CaCO₃ = 40 + 12 + (3 × 16) = 100; mass = 2 × 100 = 200 grams

Question 1: Describe a simple experiment to find the relative formula mass of a salt sample. Include safety precautions and variables to control.

Answer: To find the Mr of a salt, weigh a sample, dissolve it in water, then evaporate the water to obtain the salt. Record the mass of the salt. Control variables include temperature, purity of the salt, and amount of water used. Safety precautions include wearing gloves and goggles to handle chemicals safely.

Question 1: A student measures 10 grams of magnesium sulfate (MgSO₄) and finds it contains 2.5 moles. Does this data support the calculated Mr? Atomic masses: Mg = 24. S = 32, O = 16.

Answer: Mr of MgSO₄ = 24 + 32 + (4 × 16) = 120. Mass of 1 mole = 120 g; therefore, 2.5 moles should weigh 300 g. Since the student measured only 10 g, the data does not support the expected Mr value, indicating an error or impurity.

Question 1: How is the concept of Relative Formula Mass used in pharmaceutical drug formulation?

Answer: It helps determine the correct amounts of each chemical component to ensure proper dosage and efficacy, by calculating the Mr of active ingredients and excipients.