Question 1: Define a heating curve and explain what it illustrates about a substance as it is heated.

Answer: A heating curve is a graph that shows how the temperature of a substance changes over time as it is heated, illustrating phase changes and temperature increases.

Question 2: During a cooling curve, what is happening at the flat segments of the graph?

Answer: The flat segments represent phase changes where the temperature remains constant while the substance transitions between states, such as melting or boiling.

Question 3: What particle behavior explains the temperature plateau during melting?

Answer: Particles are gaining enough energy to change from solid to liquid, so energy is used for breaking bonds rather than increasing temperature.

Question 4: Calculate the amount of heat energy required to raise 200 g of water from 20°C to 100°C. (Specific heat capacity of water = 4.18 J/g°C)

Answer: Q = mass × specific heat capacity × temperature change = 200 g × 4.18 J/g°C × (100°C - 20°C) = 200 × 4.18 × 80 = 66,880 Joules

Question 5: Identify the phase change that occurs when water vapor condenses into liquid water.

Answer: Condensation

Question 6: Which variable primarily affects the shape of a heating curve?

Answer:

Question 7: Fill in the blank: The heat energy needed to change a substance from liquid to gas at its boiling point is called the __________ heat.

Answer: latent

Question 8: Explain why the temperature of a substance remains constant during a phase change, such as boiling.

Answer: During a phase change, energy is used to break or form bonds between particles rather than increasing their kinetic energy. As a result, the temperature stays constant until the entire sample has undergone the phase change.

Question 9: Describe a simple experiment to observe a heating curve of water, including the variables you would control and safety precautions.

Answer: You could heat a sample of water in a transparent container on a stove, recording temperature at regular intervals with a thermometer. Control variables include the amount of water and heating rate. Safety precautions include handling hot equipment carefully, using heat-resistant gloves, and ensuring the container is stable to prevent spills.

Question 10: In industries such as food processing or manufacturing, why is understanding heating and cooling curves important?

Answer: Understanding heating and cooling curves helps control temperature processes precisely, ensuring proper phase changes, preventing overheating or underheating, and maintaining product quality and safety.