Question 1: Surface area refers to the total area of the exposed surface of a substance. Increasing the surface area of a solid reactant typically increases the rate of reaction because more particles are available to collide and react. This principle is crucial in industries such as catalysts and pharmaceuticals.

Answer: Surface area is the total exposed surface of a substance; increasing it usually increases reaction rate because more particles can collide simultaneously.

Question 1: Define surface area in the context of a solid reactant.

Answer: Surface area is the total area of the outer surface of a solid substance.

Question 2: Explain why increasing the surface area of a solid reactant can speed up a chemical reaction.

Answer: Increasing surface area provides more contact points for particles to collide, increasing the likelihood of reactions occurring and thus speeding up the reaction.

Question 3: Name one industrial process where surface area plays a crucial role.

Answer: Catalytic cracking in oil refineries.

Question 1: A cube of aluminium has an edge length of 2 cm. Calculate its total surface area in square centimetres. (Formula: Surface area of a cube = 6 × edge length²)

Answer: 24 cm²

Question 2: If a spherical sulphur particle has a radius of 0.5 cm, calculate its surface area. (Formula: Surface area of a sphere = 4πr²; Use π ≈ 3.14)

Answer: 12.56 cm²

Question 1: Describe a simple experiment to investigate how surface area affects the rate of reaction between marble chips and hydrochloric acid. Include the variables you would control and safety precautions.

Answer: A suitable experiment involves reacting different sizes of marble chips (e.g., powdered, small fragments, large pieces) with a fixed volume and concentration of hydrochloric acid. Measure the time taken for the reaction to complete (e.g., by observing effervescence). Control variables include temperature, acid concentration, and volume. Safety precautions include wearing goggles, gloves, and handling acids carefully.

Question 1: A series of experiments measured the reaction time for different particle sizes of calcium carbonate reacting with acid. The data are as follows: - Fine powder: 30 seconds - Small chips: 60 seconds - Large chunks: 150 seconds Explain how the surface area of the calcium carbonate particles influences the reaction time.

Answer: Smaller particles have a larger surface area relative to their volume, providing more contact points for the acid to react. This increased surface area reduces the reaction time. Larger chunks have less surface area, resulting in longer reaction times.

Question 1: Explain why powdered zinc reacts faster with hydrochloric acid than a lump of zinc metal. Include references to surface area and collision frequency in your explanation. (6 marks)

Answer: Powdered zinc has a much larger surface area compared to a lump of zinc, meaning more zinc particles are exposed and available for reaction. This increased surface area leads to a higher frequency of successful collisions between zinc atoms and acid molecules, thus increasing the reaction rate. In contrast, a lump of zinc has less surface area exposed, resulting in fewer collisions and a slower reaction.

Question 1: Describe how increasing the surface area of a catalyst can improve industrial processes, providing an example of such a process.

Answer: Increasing the surface area of a catalyst exposes more active sites for reactions, enhancing efficiency. For example, in catalytic converters for cars, platinum and other metals are used as finely divided powders to maximise surface area and improve the breakdown of pollutants.