Question

Define triple point of water

Answer 1

The temperature and pressure at which a substance can exist in equilibrium in the liquid, solids and gaseous state. The trip point of water is at 0.01°C and 4.58 mm of a mercury and is used to calibrate thermometers.

Answer 2

Triple point of water
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The triple point is defined as the single combination of temperature and pressure at which the solid, liquid and gaseous phases of a given substance are all at equilibrium with one another.

The triple point of pure water is at 0.01°C (273.16K, 32.01°F) and a partial vapor pressure of 611.657 pascals (6.11657 mbar; 0.00603659 atm).

The gas–liquid–solid triple point of water coincides to the minimum pressure at which liquid water can exist.