Question 1: Define a heating curve and explain what it represents in terms of the particle model of matter.

Answer: A heating curve is a graph showing how the temperature of a substance changes as it is heated, indicating phase changes and temperature increases according to the particle model.

Question 2: Describe what occurs at a plateau (flat section) on a heating or cooling curve.

Answer: At a plateau, the substance is undergoing a phase change (e.g., melting or boiling) where the temperature remains constant while energy is used to change the state.

Question 3: Explain why the temperature does not increase during a phase change.

Answer: Because the energy supplied is used to break or form bonds between particles during the phase change, not to increase temperature.

Question 4: What is the main difference between a heating curve and a cooling curve?

Answer: A heating curve shows temperature increase as energy is added, while a cooling curve shows temperature decrease as energy is removed.

Question 1: Calculate the amount of heat energy required to raise the temperature of 2 kg of water from 20°C to 100°C. (Specific heat capacity of water = 4200 J/kg°C)

Answer: Q = m × c × ΔT = 2 kg × 4200 J/kg°C × (100°C - 20°C) = 2 kg × 4200 J/kg°C × 80°C = 672,000 Joules

Question 2: A 0.5 kg piece of aluminium is cooled from 150°C to 50°C. Calculate the heat lost during cooling. (Specific heat capacity of aluminium = 900 J/kg°C)

Answer: Q = m × c × ΔT = 0.5 kg × 900 J/kg°C × (50°C - 150°C) = 0.5 kg × 900 J/kg°C × (-100°C) = -45,000 Joules (heat lost)

Question 1: Describe an experiment to measure the specific heat capacity of a substance using heating curves. Include variables to control and safety precautions.

Answer: The experiment involves heating a sample of the substance with a known power source while recording temperature over time. Variables include mass, power supplied, and insulation. Control variables include ambient temperature and measurement timing. Safety precautions include avoiding direct contact with hot equipment, ensuring proper insulation, and handling electrical devices safely.

Question 1: A substance's heating curve shows a flat section at 80°C lasting for 10 minutes while 500 J of energy is supplied. What phase change is occurring, and what does this tell you about the substance?

Answer: The flat section indicates a phase change, likely melting or boiling, where energy is used to change the state without increasing temperature. The duration and energy suggest the substance is undergoing a phase transition at 80°C.

Question 1: Describe in detail what occurs at each stage of a heating curve for water from ice to steam, including energy changes and particle behaviour.

Answer: Initially, ice warms as energy is absorbed, particles move faster until melting point is reached. During melting, temperature remains constant while energy breaks bonds. Once fully melted, water heats again until boiling point, where temperature remains constant during vaporisation as particles transition to gas. After boiling, the water's temperature rises again as it heats to steam, with particles moving faster.

Question 1: Explain how knowledge of heating and cooling curves is used in designing efficient heating systems for homes.

Answer: Heating and cooling curves help engineers determine the energy needed to raise temperatures and manage phase changes, ensuring heating systems are designed to operate efficiently, avoid overheating, and precisely control temperature changes.