Question 1: Define activation energy in your own words.

Answer: The minimum amount of energy that particles must have for a reaction to occur.

Question 2: Explain why some reactions are faster than others in terms of activation energy.

Answer: Reactions with lower activation energy occur faster because more particles can reach the energy barrier at a given temperature.

Question 3: What is the effect of a catalyst on activation energy?

Answer: A catalyst decreases the activation energy, making the reaction faster.

Question 1: The rate constant (k) for a reaction doubles when the temperature increases from 300K to 310K. Assuming the Arrhenius equation applies, estimate the approximate activation energy (Ea) in kilojoules per mole. Use the formula: ln(k2/k1) = (Ea/R) * (1/T1 - 1/T2). (R = 8.314 J/mol·K)

Answer: Approximately 54 kJ/mol

Question 2: A reaction has an activation energy of 75 kJ/mol. Calculate how much faster the reaction would be at 350K compared to 300K, assuming the Arrhenius equation applies and the rate constants are proportional to the reaction rate.

Answer: Approximately 8.3 times faster

Question 1: Describe a simple experiment to measure the activation energy of a reaction involving magnesium and hydrochloric acid. Include the variables you would control and safety precautions you should take.

Answer: Students could measure the time taken for magnesium to react with hydrochloric acid at different temperatures, controlling variables such as acid concentration and magnesium surface area. Safety precautions include wearing goggles, gloves, and working in a well-ventilated area to handle acids safely.

Question 1: A reaction's rate increases significantly when the temperature is raised from 290K to 310K. The measured rate constants are k1 = 0.02 s⁻¹ at 290K and k2 = 0.15 s⁻¹ at 310K. Determine the approximate activation energy in kilojoules per mole using the Arrhenius equation.

Answer: Approximately 65 kJ/mol

Question 1: Explain how the concept of activation energy is important in the industrial production of chemicals, such as the synthesis of ammonia via the Haber process.

Answer: Understanding activation energy allows industries to optimise temperature and catalyst use to increase reaction rates and efficiency in chemical synthesis.

Question 2: Describe how catalysts are used in everyday life to lower activation energy and make reactions more efficient.

Answer: Catalysts, such as enzymes in biological systems or catalytic converters in cars, lower activation energy, enabling reactions to occur faster at lower temperatures.