Boiling point at any pressure calculator
Calculator finds out boiling point under selected pressure using Clausius-Clapeyron's equation and reference data for given substance. For example, you can find out what is water's boiling point in high mountains, where the pressure is lower.

# Beta version

BETA TEST VERSION OF THIS ITEM
This online calculator is currently under heavy development. It may or it may NOT work correctly.
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However, please VERIFY all results on your own, as the level of completion of this item is NOT CONFIRMED.
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# Input data

 Reference (known) boiling point °C Pressure for reference boiling point hPa Enthalpy of vaporization of substance kJ/mol Substance aluminum (pure)acetoneethanolwater 25°Cn-hexanemethanolbenzenediethyl etheren-pentanen-heptanen-octanen-nonanen-decaneundecanedodecanetridecanetetradecanehexadecanepropan-2-ol (isopropyl alcohol)hexafluoronenzeneethanolmethanolpropan-2-ol (isopropyl alcohol)ammoniaphosphineammoniamethanepropanen-buthanephosphinemethanen-hexanepropanen-buthanebenzenen-pentanen-heptanen-octanen-nonanen-decaneundecanedodecanetridecanetetradecanehexadecaneoctadecaneisocane (eicosane)naphthalenediethyl etherehexafluoronenzeneoctadecaneisocane (eicosane)naphthaleneOther - custom values Target pressure hPa

# Results

 Boiling point under target pressure 81.905732166°C

# Some facts

• If we know the boiling point of the substance at some specific pressure (tables usually give the value under the so-called normal pressure i.e. 1013,25 hPa) and enthalpy of vaporization (molar heat of evaporation), then we can estimate the boiling point under another, selected pressure.
• The relationship between pressure change and temperature change during evaporation (in general: phase transformation) is described by Clausius-Clapeyron equation. In the basic differential form, it looks as follows:
$\dfrac{dp}{dT} = \dfrac{L}{T\Delta V}$
where:
• $\dfrac{dp}{dT}$ - derivative of pressure after temperature under conditions of phase change equilibrium,
• $L$ - heat of phase transformation,
• $T$ - absolute temperature (in Kelvins),
• $\Delta V$ - change of volume accompanying the phase change.
• In case of transformation of liquid into gas we can obtain the following relationship (after applying several approximations and integration):
$ln\left(\dfrac{p_2}{p_1}\right) = -\dfrac{\Delta H}{R}\left(\dfrac{1}{T_2} - \dfrac{1}{T_1}\right)$
where:
• $p_1$ - pressure at state 1,
• $p_2$ - pressure at state 2,
• $T_1$ - boiling point at state 1 (under pressure $p_1$),
• $T_2$ - boiling point at state 2 (under pressure $p_2$),
• $R$ - gas constant,
• $\Delta H$ - enthalpy of evaporation of substance.
• Such an equation can be directly used to determine the boiling point under any pressure:
$T = \left[\dfrac{1}{T_{ref}} - R \dfrac{ln \left(\frac{p}{p_{ref}}\right)}{\Delta H}\right]^{-1}$
• $T_{ref}$ - known (reference) boiling point (under pressure $p_{ref}$),
• $p_{ref}$ - known (reference) pressure,
• $R$ - gas constant,
• $\Delta H$ - enthalpy of vaporization of substance,
• $p$ - the pressure for which we want to estimate the boiling point,
• $T$ - the boiling point under selected pressure.