Look up the melting/freezing and boiling point of common substances at normal atmospheric pressure, or calculate how much lower water actually boils at your altitude.
| Substance | Melting/Freezing | Boiling |
|---|---|---|
| Water | 0°C / 32°F | 100°C / 212°F |
| Ethanol (alcohol) | -114°C / -173°F | 78°C / 173°F |
| Mercury | -39°C / -38°F | 357°C / 674°F |
| Nitrogen | -210°C / -346°F | -196°C / -320°F |
| Oxygen | -218°C / -361°F | -183°C / -297°F |
| Helium | n/a below ~25 atm | -269°C / -452°F |
| Hydrogen | -259°C / -434°F | -253°C / -423°F |
| Carbon Dioxide (dry ice) | — | Sublimes at -78°C / -109°F |
| Ammonia | -78°C / -108°F | -33°C / -28°F |
| Acetone | -95°C / -139°F | 56°C / 133°F |
| Methanol | -98°C / -144°F | 64°C / 148°F |
| Glycerin | 18°C / 64°F | 290°C / 554°F |
| Aluminum | 660°C / 1221°F | 2470°C / 4478°F |
| Lead | 328°C / 621°F | 1749°C / 3180°F |
| Copper | 1085°C / 1985°F | 2562°C / 4643°F |
| Silver | 962°C / 1763°F | 2162°C / 3924°F |
| Gold | 1064°C / 1948°F | 2856°C / 5173°F |
| Iron | 1538°C / 2800°F | 2862°C / 5188°F |
| Tungsten | 3422°C / 6192°F | 5555°C / 10031°F |
| Table Salt (NaCl) | 801°C / 1474°F | 1465°C / 2669°F |
| Butter | 32–35°C / 90–95°F | Smokes before boiling |
| Beeswax | 62–64°C / 144–147°F | — |
No substance matches that search.
Tungsten has the highest melting point of any metal; helium is the only substance that won't solidify at normal pressure no matter how cold it gets — it needs about 25 atmospheres.
At the summit of Mount Everest (8,849 m), this puts water's boiling point around 70°C (158°F) — close to the ~71°C (160°F) climbers actually report.
Boiling happens when a liquid's vapor pressure equals the surrounding air pressure. Air pressure drops as altitude increases, so water reaches that equal point — and starts boiling — at a lower temperature. At the summit of Mount Everest, water boils at around 70°C (158°F) instead of 100°C.
Only by a tiny, practically unnoticeable amount. Freezing/melting is far less pressure-sensitive than boiling, so water still freezes at essentially 0°C (32°F) at any altitude you'd encounter on Earth's surface.
At normal atmospheric pressure, solid CO₂ (dry ice) skips the liquid phase entirely and goes straight to gas — a process called sublimation — at about -78.5°C (-109°F). Liquid CO₂ only exists above about 5.1 atmospheres of pressure.
It uses the standard atmosphere pressure model and the Clausius–Clapeyron relation for water, which is accurate to within roughly a degree for elevations up to about 5,000 m (16,000 ft). Real-world weather (a passing low or high pressure system) shifts the true local boiling point by a further degree or so either way.
