While ice is melting at 0°C, what happens to the heat energy being added?
AIt increases the temperature of the ice
BIt escapes to the surroundings
CIt breaks bonds between water molecules, changing solid to liquid
DIt is stored as kinetic energy in the ice
During melting, added heat energy goes into breaking the intermolecular bonds that hold the solid structure together. Temperature remains at 0°C until all the ice has melted.
Question 2 True / False
Steam at 100°C can cause a worse burn than liquid water at 100°C.
TTrue
FFalse
Answer: True
Steam carries additional latent heat energy (2,260 kJ/kg) that it releases when it condenses on your skin. Liquid water at 100°C does not carry this extra energy.
Question 3 Short Answer
How much energy is needed to melt 2 kg of ice at 0°C? (Heat of fusion of water = 334 kJ/kg)
Think about your answer, then reveal below.
Model answer: 668 kJ, because Q = mL = 2 × 334 = 668 kJ.
The energy for a phase change is Q = mL, where L is the latent heat. For melting: Q = 2 kg × 334 kJ/kg = 668 kJ. This energy melts the ice without changing its temperature.