Question 1: Define activation energy and explain its importance in the context of fuel combustion inside an engine.

Answer: Activation energy is the minimum energy required for a chemical reaction to occur. In automotive fuel combustion, it determines how easily fuel ignites, affecting engine efficiency and performance.

Question 2: Describe how a catalyst affects the activation energy of a chemical reaction in an automotive catalytic converter.

Answer: A catalyst provides an alternative reaction pathway with a lower activation energy, allowing reactions to occur more easily at lower temperatures in the catalytic converter.

Question 3: In an energy profile diagram for fuel combustion, what does the peak represent?

Answer: The peak represents the activation energy barrier that must be overcome for combustion to proceed.

Question 1: Given that the energy of reactants is 50 kJ/mol, the energy of the transition state is 150 kJ/mol, and the energy of products is 40 kJ/mol, calculate the activation energy for the reaction.

Answer: Activation energy = Energy of transition state - Energy of reactants = 150 kJ/mol - 50 kJ/mol = 100 kJ/mol

Question 2: If a catalytic converter reduces the activation energy of a reaction from 120 kJ/mol to 80 kJ/mol, by what percentage has the activation energy been reduced?

Answer: Percentage reduction = [(120 - 80) / 120] × 100 = (40 / 120) × 100 = 33.33%

Question 1: Design a simple experimental setup to investigate how temperature affects the activation energy of a fuel ignition reaction. Include variables to control, variables to measure, and safety precautions.

Answer: Students should describe using a controlled environment with a thermometer and ignition source, varying temperature systematically, measuring ignition time or temperature at ignition, and emphasising safety measures such as wearing eye protection, working in a well-ventilated area, and handling combustion materials carefully.

Question 1: A study measures the energy required to ignite different automotive fuels. Fuel A has an activation energy of 90 kJ/mol, while Fuel B has an activation energy of 70 kJ/mol. Which fuel ignites more easily, and why?

Answer: Fuel B ignites more easily because it has a lower activation energy, meaning less energy is needed for ignition.

Question 2: Explain how lowering activation energy in automotive reactions can impact engine efficiency and emissions.

Answer: Lowering activation energy allows reactions to occur more readily at lower temperatures, improving engine efficiency and reducing harmful emissions by ensuring more complete combustion.

Question 1: Explain how modern automotive catalysts reduce the activation energy of harmful emissions reactions, and discuss the environmental benefits.

Answer: Catalysts provide an alternative pathway with lower activation energy for reactions that convert pollutants into less harmful substances, reducing emissions like carbon monoxide and nitrogen oxides, thereby benefiting the environment.

Question 2: Discuss the potential impact on fuel efficiency if technological advancements successfully reduce the activation energy of fuel combustion reactions.

Answer: Reducing activation energy could allow combustion to occur more completely at lower temperatures, potentially increasing fuel efficiency, reducing fuel consumption, and lowering emissions. However, it requires balancing to prevent engine knocking or unsafe reactions.