Question 1: Define a catalyst and explain its role in a chemical reaction.

Answer: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It provides an alternative reaction pathway with lower activation energy.

Question 2: Describe the mechanism by which a catalyst typically lowers the activation energy of a reaction.

Answer: A catalyst provides an alternative pathway with a lower activation energy, often by forming temporary bonds with reactants, which facilitates the formation of products more easily.

Question 1: In an experiment, the reaction rate of the decomposition of hydrogen peroxide was measured with and without a manganese dioxide catalyst. The initial rates were: without catalyst = 0.02 mol/s, with catalyst = 0.15 mol/s. Calculate the fold increase in reaction rate due to the catalyst.

Answer: 7.5

Question 2: A catalytic converter in a car uses platinum as a catalyst to convert harmful gases into less harmful substances. Explain why platinum is an ideal catalyst for this process and mention one environmental benefit.

Answer: Platinum is an ideal catalyst because it is highly active, durable, and resistant to corrosion. It speeds up reactions without being consumed. An environmental benefit is the reduction of toxic gases like carbon monoxide into less harmful substances such as carbon dioxide and nitrogen oxides into nitrogen and oxygen.

Question 1: Design a simple experiment to test the effect of a catalyst on the rate of a reaction involving hydrochloric acid and magnesium. List the variables involved and safety precautions you would take.

Answer: The experiment involves adding a fixed amount of magnesium ribbon to hydrochloric acid in a conical flask, with and without a catalyst like manganese dioxide. Variables include the presence of catalyst (independent), reaction time or gas volume (dependent), concentration of acid, and surface area of magnesium (controlled). Safety precautions include wearing safety goggles, gloves, and working in a well-ventilated area to handle acids and gases safely.

Question 2: Explain how catalysts are used in the industrial production of ammonia via the Haber process, and state one benefit of this application.

Answer: In the Haber process, an iron catalyst is used to speed up the reaction between nitrogen and hydrogen gases at high temperature and pressure. This allows for efficient ammonia production. A benefit is the increased yield, making the process economically viable and supporting fertiliser manufacturing.

Question 1: Multiple choice: Which of the following is NOT a characteristic of a good catalyst? A) It is consumed during the reaction B) It provides an alternative reaction pathway C) It is not used up in the reaction D) It speeds up the reaction rate

Answer: A) It is consumed during the reaction

Question 2: Fill in the blank: Catalysts that are used in industry often contain __________ metals such as platinum or palladium to enhance their effectiveness.

Answer: transition