IGCSE Chemistry – Chemical Energetics Worksheet

IGCSE Chemistry – Chemical Energetics

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Question 1: Multiple Choice

1. When a chemical reaction absorbs heat from the surroundings, it is called: A) Endothermic B) Exothermic C) Isothermic D) Thermogenic

Question 2: Fill in the Blanks 2. In an exothermic reaction, the surroundings __________ heat and the temperature of the surroundings __________.

Question 3: Short Answer 3. Explain the difference between endothermic and exothermic reactions, providing an example for each.

Question 4: Calculation 4. Calculate the energy change when 2 moles of methane (CH₄) are burned completely in oxygen according to the following equation: CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) ΔH = -890 kJ/mol

Question 5: Application 5. Consider a reaction where 50.0 g of sodium hydroxide (NaOH) is dissolved in 200 mL of water, and the temperature of the solution increases from 25°C to 40°C. Calculate the energy change for this process. (Assume the density of water is 1 g/mL and specific heat capacity of water is 4.18 J/g°C)

Question 6: Diagram Analysis 6. Study the energy profile diagram below and answer the questions. (Insert a simple energy profile diagram with reactants and products labeled, along with activation energy.)

a) Identify the reactants and products. b) Label the activation energy on the diagram. c) Determine whether the reaction is endothermic or exothermic. d) Explain what the activation energy represents in a chemical reaction.

Question 7: Research and Analysis 7. Research an industrial process that involves an exothermic reaction. Explain the process, the reaction involved, and why the reaction being exothermic is beneficial for the industry.

Question 8: Critical Thinking 8. Discuss why it is important for scientists and engineers to understand the concept of energy changes in chemical reactions, especially in fields such as environmental science and pharmaceuticals.