Boiling Point

What is Boiling Point?

The temperature at which a liquid's vapor pressure equals the surrounding pressure, so it turns to vapor throughout its volume rather than just evaporating at the surface. Lower the surrounding pressure — like at altitude — and it drops.

The five clues

Engineerdle #63 described Boiling Point with five clues, revealed one at a time from hardest to most direct. Each clue points at a different property of the concept.

1. 01A temperature that isn't fixed — it shifts with the surrounding pressure.
2. 02Climb a tall mountain and this temperature for water actually drops.
3. 03It's the temperature at which a liquid's vapor pressure matches the pressure around it.
4. 04For water at sea level, everyone learns it's 100°C.
5. 05The temperature at which a liquid turns to vapor throughout its whole volume, not just at the surface.