Practice question · Multiple choice
Why does water boil at a lower temperature at high altitude?
Hints
- Boiling is a condition relating two pressures.
- A liquid boils when its vapour pressure matches the external pressure.
Show the answer
D. The external pressure is lower, so a lower vapour pressure suffices
Why
Boiling happens when vapour pressure equals the surrounding pressure. Lower atmospheric pressure means that condition is met at a lower temperature, which is why cooking takes longer on a mountain and why a pressure cooker works.
Practise Physical Equilibria and Phase Diagrams
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