Question 1: Surface area refers to the total area of the exposed surface of a substance. Explain how increasing the surface area of a reactant affects the rate of a chemical reaction.

Answer: Increasing the surface area exposes more particles to collision, increasing the frequency of successful collisions and thus increasing the reaction rate.

Question 1: Define 'surface area' in the context of chemical reactions.

Answer: Surface area is the total area of the outer surface of a substance exposed to react with other substances.

Question 2: Describe how crushing a solid reactant affects its reaction rate and why.

Answer: Crushing a solid increases its surface area, exposing more particles to collisions, which increases the frequency of successful collisions and accelerates the reaction.

Question 1: A piece of aluminium foil has a mass of 10 grams and a thickness of 0.1 mm. Given the density of aluminium is 2.7 g/cm³, calculate the total surface area of the foil in cm².

Answer: First, calculate volume: Volume = mass / density = 10 g / 2.7 g/cm³ ≈ 3.70 cm³. Next, find area: Volume = area × thickness, so area = Volume / thickness = 3.70 cm³ / 0.01 cm = 370 cm².

Question 2: If grinding a block into smaller pieces increases its surface area from 200 cm² to 800 cm², by what factor has the surface area increased?

Answer: Increase factor = 800 / 200 = 4.

Question 1: Outline a simple experimental setup to investigate how surface area affects the reaction rate between magnesium and hydrochloric acid. Include variables to control and safety precautions.

Answer: The experiment involves reacting magnesium pieces of different surface areas with a fixed concentration and volume of hydrochloric acid. Variables include surface area (by using granules, strips, or powder), acid concentration, and temperature. Safety precautions include wearing eye protection, gloves, and working in a well-ventilated area to handle acids safely.

Question 1: A scientist observes that doubling the surface area of a reactant results in the reaction completing twice as fast. Explain this observation with reference to collision theory.

Answer: Doubling the surface area exposes more particles for collision, increasing the number of successful collisions per unit time, which effectively doubles the reaction rate as per collision theory.

Question 1: Explain how the surface area of catalytic converters in cars improves their efficiency and reduces harmful emissions.

Answer: Catalytic converters have a large surface area with catalysts like platinum, palladium, and rhodium. This maximises contact with exhaust gases, increasing reaction rates for converting pollutants into less harmful substances, thereby improving efficiency and reducing emissions.

Question 2: In the food industry, why is increasing the surface area of powdered ingredients important in processes like baking or flavour extraction?

Answer: Increasing surface area allows for better contact with other ingredients or solvents, speeding up chemical reactions like baking or extraction processes, leading to more efficient and uniform results.