Change of State & Latent Heat

Phase change occurs at constant temperature; latent heat hides as molecular rearrangement.

Concept

Change of State & Latent Heat is a foundational idea in this chapter. The defining relationship is:

$Q = m L$

Latent heat of fusion of ice = 334 kJ/kg; of vaporisation of water = 2260 kJ/kg.

Worked Application

Apply the formula to a typical problem from your textbook. Identify the knowns, plug into the equation, and check that the units work out. Always sanity-check the magnitude before accepting an answer.

Common Confusions

• Confusing the variables in the formula — re-read the symbol definitions in the chapter.
• Forgetting unit conversions (cm vs m, g vs kg).
• Ignoring sign conventions where direction matters.

Key Takeaways

• Master the formula $Q = m L$ and one canonical example.
• See the chapter index for full derivations, traps and exam-grade problems.