Question 1: Define latent heat and explain its role during a phase change of a substance.

Answer: Latent heat is the heat energy absorbed or released by a substance during a phase change without changing temperature. It is involved in changing the state of the substance, such as melting or boiling.

Question 2: What is the primary difference between sensible heat and latent heat?

Answer: Sensible heat causes a change in temperature of a substance, while latent heat involves a change in the state of the substance without changing its temperature.

Question 3: Explain why the temperature of water remains constant during boiling despite continuous heat input.

Answer: The heat energy is used as latent heat to convert water from liquid to vapor, so the temperature remains constant until the phase change is complete.

Question 1: Calculate the amount of heat required to convert 3 kg of ice at -10°C to water at 0°C. Specific heat capacity of ice = 2100 J/kg°C, latent heat of fusion for ice = 334,000 J/kg.

Answer: Q = mcΔT + mLf; Q = (3)(2100)(10) + (3)(334000) = 63,000 + 1,002,000 = 1,065,000 Joules

Question 2: A stove supplies 2,500 Joules of heat to boiling water. How much water (in kg) can be vaporized if the latent heat of vaporization of water is 2,260,000 J/kg?

Answer: m = Q / Lv; m = 2500 / 2,260,000 ≈ 0.00111 kg

Question 1: Outline a simple experiment to measure the latent heat of vaporization of water, including variables to control and safety precautions.

Answer: An experiment can involve heating a known mass of water in a calorimeter until boiling, measuring the heat supplied and mass vaporized to calculate latent heat. Control variables include initial water temperature and heating rate. Safety precautions include using heat-resistant gloves, ensuring proper ventilation, and handling hot equipment carefully.

Question 1: A 0.5 kg sample of water is heated from 20°C to boiling point at 100°C, then vaporized completely using 1,130,000 Joules of heat. Calculate the latent heat of vaporization of water based on this data.

Answer: Q = mcΔT + mL; Q - heat supplied, m = 0.5 kg, ΔT = 80°C, Q = 1,130,000 J First, heat used to raise temperature: (0.5)(4200)(80) = 168,000 J Remaining heat for vaporization: 1,130,000 - 168,000 = 962,000 J Latent heat, Lv = Q / m = 962,000 / 0.5 = 1,924,000 J/kg

Question 1: Explain how latent heat is utilized in the process of refrigeration and air conditioning systems.

Answer: Refrigeration and air conditioning systems use the absorption and release of latent heat during phase changes of refrigerants to transfer heat away from or into a space, effectively cooling or heating the environment.

Question 2: Describe a real-world scenario where understanding latent heat is crucial for safety or efficiency.

Answer: Understanding latent heat is crucial when designing boilers or steam turbines, where controlling phase changes and heat transfer ensures safety, efficiency, and proper operation, preventing accidents like explosions or energy losses.