Question 1: Define oxidation in terms of electron transfer.

Answer: Oxidation is the loss of electrons by a substance during a chemical reaction.

Question 2: Explain the process of reduction in a redox reaction.

Answer: Reduction is the gain of electrons by a substance during a chemical reaction.

Question 3: In the reaction Zn + Cu²⁺ → Zn²⁺ + Cu, which substance is oxidised and which is reduced? Justify your answer.

Answer: Zinc is oxidised because it loses electrons to form Zn²⁺; copper ions are reduced because they gain electrons to form copper metal.

Question 4: Identify the oxidation state change for aluminium in the reaction 2Al + 3Cl₂ → 2AlCl₃.

Answer: Aluminium's oxidation state changes from 0 (elemental aluminium) to +3 in AlCl₃.

Question 5: Describe the role of electrons in oxidation and reduction processes.

Answer: Electrons are transferred from the oxidised substance to the reduced substance during a redox reaction.

Question 1: Describe the mechanism of corrosion of iron and how oxidation is involved.

Answer: Corrosion of iron involves oxidation of iron atoms to form iron oxides, typically through exposure to oxygen and moisture, where iron loses electrons to oxygen.

Question 2: Identify a common industrial process where redox reactions are essential, and explain its significance.

Answer: Electroplating uses redox reactions to deposit a metal layer onto objects, preventing corrosion and improving appearance.

Question 3: Explain how batteries utilise oxidation and reduction to generate electrical energy.

Answer: In batteries, oxidation occurs at the anode and reduction at the cathode, with electrons flowing through an external circuit to produce electricity.

Question 4: Which safety precautions should be taken when handling reactive metals such as sodium or potassium? List at least two.

Answer: Handle with dry, inert atmospheres to prevent reactions with moisture; wear protective gloves and eye protection.

Question 1: Calculate the number of electrons transferred when 5 grams of magnesium (Mg, molar mass = 24.3 g/mol) is oxidised to Mg²⁺.

Answer: Number of moles = 5 / 24.3 ≈ 0.206 mol; electrons transferred = 0.206 mol × 2 electrons per atom ≈ 0.412 mol electrons.

Question 2: A metal strip is immersed in a solution, and it loses 0.05 mol of electrons over 10 minutes. Describe what this indicates about the metal's reactivity.

Answer: It indicates that the metal is undergoing oxidation, releasing electrons and thus is reactive.

Question 3: In an experiment, a zinc electrode loses 0.1 mol of electrons during electrolysis. What is the equivalent mass of zinc involved? (Zinc molar mass = 65.38 g/mol, valency = 2).

Answer: Equivalent mass = molar mass / valency = 65.38 / 2 ≈ 32.69 g; mass involved = 0.1 mol × 32.69 g ≈ 3.27 g.

Question 1: Provide an example of how oxidation and reduction are involved in the functioning of a car battery.

Answer: In a car battery, the oxidation of lead at the anode and reduction of lead dioxide at the cathode generate electrical energy to power the vehicle.

Question 2: Explain the importance of redox reactions in the process of bleaching in industries.

Answer: Bleaching involves oxidation reactions where colour-causing compounds are oxidised to colourless substances, making products like paper and textiles white.

Question 3: Describe a safety consideration when using strong oxidising agents such as potassium permanganate in laboratory experiments.

Answer: Strong oxidising agents can react vigorously with organic materials and reducing agents; handle with proper protective equipment and avoid contact with skin and eyes.