# What is Triple Point of Water? | Definition – Thermometry and Calorimetry

Triple Point of Water Definition:
The values of pressure and temperature at which water coexists in equilibrium in all three states of matter, i.e. ice, water and vapour is called triple point of water.

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## What is Triple Point of Water? | Definition – Thermometry and Calorimetry

Triple point of water is 273 K temperature and 0.46 cm of mercury pressure.

The triple point of water, T3 = 273.16 K, is the standard fixed-point temperature for the calibration of thermometers. This agreement also sets the size of the kelvin as 1/273.16 of the difference between the triple-point temperature of water and absolute zero.

### Why is the Triple Point of Water Important

It is also important to note that the triple point of water correlates with the pressure necessary for liquid water to exist. Because ice is less dense than liquid water, ice frozen at pressures below the triple point will sublime directly into water vapor.

Thermometry and Calorimetry:
The thermometer is a device used to check the temperature of an object. This branch of measurement of the temperature of a substance is called thermometry. It is measured in degrees or Fahrenheit, usually.

Calorimetry also means the measurement of heat but in joules. It states the amount of heat lost by the body is the amount of heat gained by its surrounding.