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The difference of temperatures between the freezing- and boiling-points of water under standard atmospheric pressure shall be called 100 degrees. (The same increment as the Celsius scale) Thomson's best estimates at the time were that the temperature of freezing water was 273.7 K and the temperature of boiling water was 373.7 K. [33]
Boiling point (°C) K b (°C⋅kg/mol) Freezing point (°C) K f (°C⋅kg/mol) Data source; Aniline: 184.3 ... K f [2] K b [1] Water: 100.00 0.512 0.00 –1.86 K b ...
Notably, the Kelvin, Celsius, Rankine, and Fahrenheit scales were, or currently are, defined by the freezing and boiling points of water. The less common scales of Delisle, Newton, Réaumur, and Rømer were defined similarly. The triple point of water is a more commonly used standard point today.
For temperature range: 173.15 K to 273.15 K or equivalently −100 °C to 0 °C At triple point. An important basic value, which is not registered in the table, is the saturated vapor pressure at the triple point of water. The internationally accepted value according to measurements of Guildner, Johnson and Jones (1976) amounts to:
The melting point of water at 1 atmosphere of pressure is very close to 0 °C (32 °F; 273 K), and in the presence of nucleating substances the freezing point of water is close to the melting point, but in the absence of nucleators water can supercool to −40 °C (−40 °F; 233 K) before freezing.
Although the Kelvin and Celsius scales are defined using absolute zero (0 K) and the triple point of water (273.16 K and 0.01 °C), it is impractical to use this definition at temperatures that are very different from the triple point of water.
Kelvin Rankine Fahrenheit Celsius Réaumur Temperature Absolute zero: 0 K 0 °Ra −459.67 °F −273.15 °C -218.52 °Ré Freezing point of brine [a] 255.37 K 459.67 °Ra 0 °F −17.78 °C −14.224 °Ré Freezing point of water [b] 273.15 K 491.67 °Ra 32 °F 0 °C 0 °Ré Boiling point of water [c] 373.1339 K 671.64102 °Ra
In the above equation, T F is the normal freezing point of the pure solvent (273 K for water, for example); a liq is the activity of the solvent in the solution (water activity for aqueous solution); ΔH fus T F is the enthalpy change of fusion of the pure solvent at T F, which is 333.6 J/g for water at 273 K; ΔC fus p is the difference ...