Question 1: Define an exothermic reaction and describe how it appears on a reaction profile diagram.

Answer: An exothermic reaction releases energy to the surroundings, shown on a reaction profile as a decrease in energy from reactants to products.

Question 2: Explain the significance of the activation energy in a reaction profile.

Answer: Activation energy is the minimum energy required for reactants to undergo a successful collision leading to a reaction, represented as the peak of the reaction profile.

Question 3: What is the difference between an endothermic and an exothermic reaction in terms of energy change?

Answer: An endothermic reaction absorbs energy, resulting in an increase in energy from reactants to products, whereas an exothermic reaction releases energy, resulting in a decrease.

Question 1: A reaction profile shows that the energy of reactants is 50 kJ/mol and the energy of products is 40 kJ/mol. Calculate the overall energy change for this reaction.

Answer: The energy change = 40 kJ/mol - 50 kJ/mol = -10 kJ/mol (exothermic).

Question 2: If the activation energy for the forward reaction is 80 kJ/mol and the energy of reactants is 50 kJ/mol, what is the height of the activation barrier above the energy level of reactants?

Answer: Activation energy barrier = 80 kJ/mol - 50 kJ/mol = 30 kJ/mol.

Question 1: Describe a basic experiment to investigate the energy change of a reaction, including variables to control and safety precautions.

Answer: Mix reactants in a calorimeter, measure temperature change, control variables like concentration, temperature, and catalysts; wear safety goggles and gloves to handle chemicals safely.

Question 2: Explain how reaction profiles are relevant to industrial processes such as the manufacturing of chemicals or fuels.

Answer: Reaction profiles help in understanding the energy barriers and stability of reactants and products, allowing industries to optimise conditions, reduce energy costs, and improve safety by controlling reaction rates and energy release or absorption during manufacturing processes.

Question 1: A reaction profile indicates that the energy of reactants is 60 kJ/mol, the peak activation energy is 100 kJ/mol, and the energy of products is 55 kJ/mol. Describe the energy changes and whether the reaction is likely exothermic or endothermic.

Answer: The overall energy change = 55 kJ/mol - 60 kJ/mol = -5 kJ/mol, indicating an exothermic reaction; energy is released, and the activation energy is 40 kJ/mol above reactants.

Question 1: Describe the factors that influence the height of the activation energy barrier in a chemical reaction and how this affects reaction rate.

Answer: Factors include temperature, catalysts, particle size, and concentration. Lower activation energy (via catalysts) increases reaction rate by making it easier for reactants to reach the transition state, whereas higher barriers slow down the reaction.

Question 2: In the context of energy-efficient industrial processes, explain how understanding reaction profiles can help reduce energy consumption during chemical manufacturing.

Answer: By analysing reaction profiles, industries can select conditions that lower activation energies or favour exothermic pathways, optimise temperature and catalysts, and minimise energy waste, leading to more sustainable and cost-effective manufacturing.