Question 1: Define an exothermic reaction and explain what happens to the energy of the surroundings during such a reaction.

Answer: An exothermic reaction releases energy to the surroundings, causing the temperature to increase. The energy of the products is lower than that of the reactants.

Question 2: Describe the key features of a typical reaction energy profile diagram for an exothermic reaction.

Answer: It shows a rise to a peak representing activation energy, then a drop below the initial energy level, indicating energy release. The overall energy change is negative.

Question 3: What is activation energy, and why does it affect the rate of a chemical reaction?

Answer: Activation energy is the minimum energy required for reactants to form products. Higher activation energy slows down the reaction rate.

Question 4: In an endothermic reaction, does the energy of the products increase or decrease compared to the reactants? Explain.

Answer: The energy of the products increases compared to the reactants because energy is absorbed during the reaction.

Question 5: Calculate the energy change if the energy of reactants is 150 kJ and the energy of products is 180 kJ.

Answer: Energy change = Energy of products - Energy of reactants = 180 kJ - 150 kJ = +30 kJ (endothermic).

Question 6: Identify which reaction profile (exothermic or endothermic) corresponds to the following description: 'The energy of the products is less than that of the reactants, and energy is released.'

Answer: Exothermic

Question 7: Fill in the blank: The peak of the reaction energy profile represents the __________, which is the minimum energy needed for the reaction to occur.

Answer: activation energy

Question 8: Explain why a catalyst affects the reaction profile, and how it influences the activation energy.

Answer: A catalyst provides an alternative pathway with a lower activation energy, which increases the reaction rate without being consumed in the reaction. It lowers the peak of the energy profile, making it easier for reactants to convert into products.

Question 9: Describe an experiment to investigate whether a reaction is exothermic or endothermic, including safety precautions.

Answer: Mix reactants in a calorimeter and measure temperature changes. An increase in temperature indicates an exothermic reaction, while a decrease indicates an endothermic reaction. Safety precautions include wearing safety goggles, gloves, and working in a well-ventilated area to handle chemicals safely.

Question 10: In industrial applications, why is understanding reaction profiles important for designing chemical processes?

Answer: Understanding reaction profiles helps in controlling energy requirements, optimizing reaction conditions, and improving safety by predicting energy release or absorption during reactions.