Question 1: Define Collision Theory in the context of chemical reactions.

Answer: Collision Theory states that chemical reactions occur when particles collide with sufficient energy and proper orientation to break old bonds and form new ones.

Question 2: Describe two factors that increase the frequency of successful collisions between reactant particles.

Answer: Increasing temperature and increasing concentration or surface area both raise the number of successful collisions by making particles collide more often and with more energy.

Question 3: Explain why only a fraction of collisions lead to a reaction.

Answer: Because only collisions with enough energy to overcome the activation energy barrier and correct orientation result in a successful reaction.

Question 1: Calculate the minimum energy required for a reaction if the activation energy is 50 kJ/mol. Express your answer in joules.

Answer: 50,000 J/mol

Question 2: If the rate constant (k) doubles when the temperature increases from 300 K to 310 K, estimate the activation energy using the Arrhenius equation approximation. (Use the relation: rate doubles, so ln(2) ≈ 0.693).

Answer: Activation energy ≈ 70 kJ/mol

Question 1: Describe an experiment to investigate how temperature affects the rate of a reaction involving calcium carbonate and hydrochloric acid.

Answer: The experiment involves adding a fixed quantity of calcium carbonate to hydrochloric acid in a conical flask, then measuring the time taken for a set amount of gas (CO₂) to be evolved at different temperatures (e.g., 20°C, 30°C, 40°C). Variables include temperature (independent), reaction time or gas volume (dependent), and concentration of acid (controlled). Safety precautions include wearing goggles and handling acids carefully.

Question 2: Identify two variables that should be kept constant in the above experiment and explain why.

Answer: The concentration of hydrochloric acid and the amount of calcium carbonate should be kept constant to ensure that the only changing factor is temperature, allowing for accurate assessment of its effect.

Question 1: A reaction's rate increases significantly when the temperature is raised from 25°C to 35°C. Explain this observation using Collision Theory principles.

Answer: Increasing temperature raises the kinetic energy of particles, leading to more frequent and energetic collisions. More particles have sufficient energy to surpass the activation energy barrier, resulting in a faster reaction rate.

Question 1: Explain how increasing surface area can affect the rate of reaction according to Collision Theory. (6 marks)

Answer: Increasing surface area exposes more particles to collisions, thereby increasing the frequency of successful collisions. This leads to a higher reaction rate because more particles are available to react simultaneously, especially in reactions involving solids.

Question 1: Describe how Collision Theory is utilised in the industrial Haber process for synthesising ammonia.

Answer: In the Haber process, conditions such as high temperature and pressure are used to increase the frequency and energy of nitrogen and hydrogen molecule collisions, thereby increasing the rate of ammonia formation.