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Changes of State: Mechanism

≈ 25 min
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Mechanism

Follow the mechanism step by step and distinguish what causes the change from what is merely observed.

This extension applies that lens specifically to Changes of State.

Each change of state has a name and a direction:

  • Melting (solid → liquid) and freezing (liquid → solid) happen at the melting point.
  • Evaporation / boiling (liquid → gas) and condensation (gas → liquid) happen at the boiling point.
  • Sublimation (solid → gas directly) — e.g. dry ice, CO2\text{CO}_2.

Melting and boiling absorb energy (particles need energy to break apart); freezing and condensation release energy. For pure water at sea level, the melting point is 0 ∘C0\,^\circ\text{C} and the boiling point is 100 ∘C100\,^\circ\text{C}.

Chemistry — Grade 10 — Mechanism: Steam hitting a cold window and turning into water droplets is called…

Chemistry — Grade 10 — Mechanism: Which change of state releases energy to the surroundings?

Chemistry — Grade 10 — Mechanism: At sea level, what is the boiling point of pure water in ∘C^\circ\text{C}?

Name the original topic being extended by this mechanism lesson.

Which statement is the best evidence-led starting point for Changes of State: Mechanism?