Level 6: Phase changes

Heat and matter · level 6 of 8 · rough age 13-14 (a guide for parents; anyone can start anywhere)

Melting and boiling take energy without changing the temperature. In this level you put numbers on that, the latent heat, and find the energy to turn Mars ice into drinking water. Then you see why the boiling point depends on pressure, what the triple point is, how to read a phase diagram, and why liquid water is so rare on Mars today.

Lesson	You will be able to
Latent heat	Use \(Q = mL\) for melting, boiling and sublimation
Water from ice	Find the energy to turn Mars ice into warm water
Boiling point and pressure	Use vapour pressure to find the boiling point on a mountain and on Mars
The triple point	Explain the triple point, and why Mars's air is so close to it
Phase diagrams	Read the phase diagrams of water and carbon dioxide
Water on Mars	Explain where Mars's water is today, and how salt changes things

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