Enthalpy of vaporization: Difference between revisions

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{{Short description|Energy to convert a liquid substance to a gas at a given pressure}}

The '''standard enthalpy change of vaporization''', '''&Delta;_v''H''^<s>o</s>''',

{{Use American English|date = March 2019}}

also (less correctly) known as the '''heat of vaporization''' is the [[energy]]

{{Use dmy dates|date=October 2014}}

required to transform a given quantity of a substance into a gas. It is measured at the [[boiling point]] of the substance,

{{more footnotes needed|date=March 2016}}

although tabulated values are usually corrected to 298&nbsp;[[Kelvin|K]]: the correction is small, and is often smaller

[[Image:Heat of Vaporization (Benzene+Acetone+Methanol+Water).png|thumb|280px|Temperature-dependency of the heats of vaporization for [[water]], [[methanol]], [[benzene]], and [[acetone]]]]

than the [[Standard deviation|uncertainty]] in the measured value. Values are usually quoted in [[Joule|kJ]]/[[Mole (unit)|mol]],

although kJ/[[Kilogram|kg]], [[Calorie|kcal]]/mol, cal/g and [[British thermal unit|Btu]]/[[Pound (mass)|lb]] (obsolete) are also

possible, among others.

In [[thermodynamics]], the '''enthalpy of vaporization''' (symbol {{math|∆''H''_vap}}), also known as the ('''latent''') '''heat of vaporization''' or '''heat of evaporation''', is the amount of energy ([[enthalpy]]) that must be added to a [[liquid]] substance to [[Phase transition|transform]] a quantity of that substance into a [[gas]]. The enthalpy of vaporization is a function of the [[pressure]] and temperature at which the transformation ([[vaporization]] or [[evaporation]]) takes place.

The '''standard enthalpy change of condensation''' (or '''heat of condensation''') is numerically exactly equal to the

standard enthalpy change of vaporisation, but has the opposite sign: enthalpy changes of vaporisation are always positive ([[heat]] is

absorbed by the substance), whereas enthalpy changes of condensation are always negative (heat is released by the substance).

The enthalpy of vaporization is often quoted for the [[normal boiling point|normal boiling temperature]] of the substance. Although tabulated values are usually corrected to 298&nbsp;[[Kelvin|K]], that correction is often smaller than the [[Significant figures|uncertainty]] in the measured value.

The enthalpy change of vaporisation can be viewed as the energy required to overcome the [[Chemical bond#Intermolecular interactions|intermolecular interactions]]

in the liquid (or solid, in the case of [[sublimation]]). Hence [[helium]] has a particularly low standard enthalpy change of

vaporisation, 0.0845&nbsp;kJ/mol, as the [[van der Waals force]]s between helium [[atom]]s are particularly weak. One the other hand,

the [[molecule]]s in liquid [[Water (molecule)|water]] are held together by relatively strong [[hydrogen bond]]s, and its

standard enthalpy change of vaporisation, 40.8&nbsp;kJ/mol, is more than five times the energy required to heat the same

quantity of water from 0&nbsp;&deg;C to 100&nbsp;&deg;C ([[Heat capacity|''c''_p]]&nbsp;= 75.3&nbsp;J&nbsp;K^{&minus;1&nbsp;}mol^&minus;1).

Care must be taken, however, when using enthaply changes of vaporization to ''measure'' the strength of intermolecular forces,

as these forces may persist in the gas phase (as is the case with water), and so the calculated value of the [[bond strength]]

will be too low. This is particularly true of metals, which often form [[Covalent bond|covalently bonded]] molecules in the

gas phase: in these cases, the [[standard enthalpy change of atomization]] must be used to obtain a true value of the [[bond energy]].

The heat of vaporization is temperature-dependent, though a constant heat of vaporization can be assumed for small temperature ranges and for [[reduced temperature]] {{math|''T{{sub|r}}'' ≪ 1}}. The heat of vaporization diminishes with increasing temperature and it vanishes completely at a certain point called the [[critical temperature]] ({{math|1=''T{{sub|r}}'' = 1}}). Above the critical temperature, the liquid and [[vapor]] phases are indistinguishable, and the substance is called a [[supercritical fluid]].

An alternative description is to view the enthalpy change of condensation as the heat which must be released to the surroundings

to compensate for the drop in [[entropy]] when a gas condenses to a liquid. As the liquid and gas are in [[Chemical equilibrium|equilibrium]]

at the boiling point (''T''_b), [[Gibbs free energy|&Delta;_v''G'']]&nbsp;=&nbsp;0, which leads to:

::&Delta;_v''S'' = ''S''_gas &minus; ''S''_liquid = &Delta;_v''H''/''T''_b

As neither entropy nor [[enthalpy]] vary greatly with [[temperature]], it is normal to use the tabulated standard values without any

correction for the difference in temperature from 298&nbsp;K. A correction must be made if the [[pressure]] is different from 100&nbsp;[[Pascal (unit)|kPa]],

as the entropy of a gas is proportional to its pressure (or, more precisely, to its [[fugacity]]): the entropies of liquids

vary little with pressure, as the [[compressibility]] of a liquid is small.

== Units ==

These two definitions are equivalent: the boiling point is the temperature at which the increased entropy of the gas phase

Values are usually quoted in [[joule|J]]/[[mole (unit)|mol]], or kJ/mol (molar enthalpy of vaporization), although kJ/kg, or J/g (specific heat of vaporization), and older units like [[calorie|kcal]]/mol, cal/g and [[British thermal unit|Btu]]/lb are sometimes still used among others.

overcomes the intermolecular forces. As a given quatity of matter always has a higher entropy in the gas phase than in a

condensed phase (&Delta;_v''S'' is always positive), and from

== Enthalpy of condensation ==

::&Delta;''G'' = &Delta;''H'' &minus; ''T''&Delta;''S'',

The '''enthalpy of condensation''' (or '''heat of condensation''') is by definition equal to the enthalpy of vaporization with the opposite sign: enthalpy changes of vaporization are always positive (heat is absorbed by the substance), whereas enthalpy changes of condensation are always negative (heat is released by the substance).

the Gibbs free energy change falls with increasing temperature: gases are favored at higher temperatures, as is observed in practice.

== Thermodynamic background ==

[[File:Enthalpy of Zn(c,l,g).PNG|thumb|right|350px|'''Molar enthalpy of zinc''' above 298.15{{nbsp}}K and at 1{{nbsp}}atm pressure, showing discontinuities at the melting and boiling points. The enthalpy of melting (Δ''H''°m) of zinc is 7323{{nbsp}}J/mol, and the enthalpy of vaporization (Δ''H''°v) is {{val|115330|u=J/mol}}.]]

The enthalpy of vaporization can be written as

:<math>\Delta H_\text{vap} = \Delta U_\text{vap} + p\,\Delta V</math>

It is equal to the increased [[internal energy]] of the vapor phase compared with the liquid phase, plus the work done against ambient pressure. The increase in the internal energy can be viewed as the energy required to overcome the [[Chemical bond#Intermolecular interactions|intermolecular interactions]] in the liquid (or solid, in the case of [[Sublimation (chemistry)|sublimation]]). Hence [[helium]] has a particularly low enthalpy of vaporization, 0.0845&nbsp;kJ/mol, as the [[van der Waals force]]s between helium [[atom]]s are particularly weak. On the other hand, the [[molecule]]s in liquid [[Water (molecule)|water]] are held together by relatively strong [[hydrogen bond]]s, and its enthalpy of vaporization, 40.65&nbsp;kJ/mol, is more than five times the energy required to heat the same quantity of water from 0&nbsp;°C to 100&nbsp;°C ([[Heat capacity|''c''_p]]&nbsp;= 75.3&nbsp;J/K·mol). Care must be taken, however, when using enthalpies of vaporization to ''measure'' the strength of intermolecular forces, as these forces may persist to an extent in the gas phase (as is the case with [[hydrogen fluoride]]), and so the calculated value of the [[bond strength]] will be too low. This is particularly true of metals, which often form [[Covalent bond|covalently bonded]] molecules in the gas phase: in these cases, the [[enthalpy of atomization]] must be used to obtain a true value of the [[bond energy]].

An alternative description is to view the enthalpy of condensation as the heat which must be released to the surroundings to compensate for the drop in [[entropy]] when a gas condenses to a liquid. As the liquid and gas are in [[Chemical equilibrium|equilibrium]] at the boiling point (''T''_b), [[Gibbs free energy|Δ_v''G'']]&nbsp;=&nbsp;0, which leads to:

:<math>\Delta_\text{v} S = S_\text{gas} - S_\text{liquid} = \frac{\Delta_\text{v} H}{T_\text{b}}</math>

As neither entropy nor [[enthalpy]] vary greatly with temperature, it is normal to use the tabulated standard values without any correction for the difference in temperature from 298&nbsp;K. A correction must be made if the [[pressure]] is different from 100&nbsp;[[pascal (unit)|kPa]], as the entropy of an [[ideal gas]] is proportional to the logarithm of its pressure. The entropies of liquids vary little with pressure, as the [[Thermal expansion|coefficient of thermal expansion]] of a liquid is small.<ref>Note that the rate of change of entropy with pressure and the rate of thermal expansion are related by the [[Maxwell Relations|Maxwell Relation]]:

:<math>\left(\frac{\partial S}{\partial P}\right)_T = \left(\frac{\partial V}{\partial T}\right)_P.</math></ref>

These two definitions are equivalent: the boiling point is the temperature at which the increased entropy of the gas phase overcomes the intermolecular forces. As a given quantity of matter always has a higher entropy in the gas phase than in a condensed phase (<math>\Delta_\text{v} S</math> is always positive), and from

:<math>\Delta G = \Delta H - T\Delta S</math>,

the [[Gibbs free energy]] change falls with increasing temperature: gases are favored at higher temperatures, as is observed in practice.

==Vaporization enthalpy of electrolyte solutions==

Estimation of the enthalpy of vaporization of electrolyte solutions can be simply carried out using equations based on the chemical thermodynamic models, such as Pitzer model<ref>{{cite journal|last1=Ge|first1=Xinlei|last2=Wang|first2=Xidong|title=Estimation of Freezing Point Depression, Boiling Point Elevation, and Vaporization Enthalpies of Electrolyte Solutions|journal=Industrial & Engineering Chemistry Research|date=20 May 2009|volume=48|issue=10|pages=5123|doi=10.1021/ie900434h|doi-access=free}}</ref> or TCPC model.<ref name="GeWang2009">{{cite journal|last1=Ge|first1=Xinlei|last2=Wang|first2=Xidong|title=Calculations of Freezing Point Depression, Boiling Point Elevation, Vapor Pressure and Enthalpies of Vaporization of Electrolyte Solutions by a Modified Three-Characteristic Parameter Correlation Model|journal=Journal of Solution Chemistry|volume=38|issue=9|year=2009|pages=1097–1117|issn=0095-9782|doi=10.1007/s10953-009-9433-0|s2cid=96186176}}</ref>

== Selected values ==

{{more citations needed section|date=September 2018}}

=== Elements ===

<div class="thumb" style="table-layout:fixed; margin:5px 5px 5px 0; clear:both; width:98%;">

<center>

<div class="overflowbugx" style="table-layout:fixed; overflow:auto;">

<!-- Standard enthalpy changes of vaporization of the elements in kJ/mol -->

{| border="0" cellpadding="0" cellspacing="21" style="table-layout:fixed; background:{{element color|table background}}; border:1px solid {{element color|table border}}; width:80100%; max-width:2000px; margin:0 auto; padding:2px; {{{1style|}}};"

! colspan=20 style="background:{{element color|table title}}; padding:2px 4px;" | Enthalpies of vaporization of the elements

|- style="background:{{element color|table colheader}}"

!

! [[Alkali metal|1]]

! [[Alkaline earth metal|2]]

!

! [[Group 3 element|3]]

! [[Group 4 element|4]]

! [[Group 5 element|5]]

! [[Group 6 element|6]]

! [[Group 7 element|7]]

! [[Group 8 element|8]]

! [[Group 9 element|9]]

! [[Group 10 element|10]]

! [[Group 11 element|11]]

! [[Group 12 element|12]]

! [[Boron group|13]]

! [[Carbon group|14]]

! [[Nitrogen group|15]]

! [[Chalcogen|16]]

! [[Halogen|17]]

! [[Noble gas|18]]

|-

! widthcolspan=3 style="1.0%text-align:left;" | [[PeriodicGroup table(periodic grouptable)|Group]]&nbsp;&rarr;

! width="5.5%" | [[Alkali metal | 1]]

! width="5.5%" | [[Alkaline earth metal| 2]]

! width="5.5%" | [[Group 3 element | 3]]

! width="5.5%" | [[Group 4 element | 4]]

! width="5.5%" | [[Group 5 element | 5]]

! width="5.5%" | [[Group 6 element | 6]]

! width="5.5%" | [[Group 7 element | 7]]

! width="5.5%" | [[Group 8 element | 8]]

! width="5.5%" | [[Group 9 element | 9]]

! width="5.5%" | [[Group 10 element |10]]

! width="5.5%" | [[Group 11 element |11]] <!-- also [[Coinage metal|11]] -->

! width="5.5%" | [[Group 12 element |12]]

! width="5.5%" | [[Boron group |13]]

! width="5.5%" | [[Carbon group |14]]

! width="5.5%" | [[Nitrogen group |15]] <!-- also [[Pnictogen|15]] -->

! width="5.5%" | [[Chalcogen |16]]

! width="5.5%" | [[Halogen |17]]

! width="5.5%" | [[Noble gas |18]]

|-

! &darrcolspan=3 style="text-align:left;"| ↓&nbsp;[[Periodic table period|Period]]

| colspan="19"|<br />

|-

! [[Period 1 element|1]]

| {{element cell propproperty|1=H |3=0.4493690|ffff637=#ffccff|2=hydrogen |Primordial5=primordial}}

| colspan="1617"|<br />|

| {{element cell propproperty|1=He|3=0.0845 08|ffff637=#ffccff|2=helium |Primordial5=primordial}}

|-

! [[Period 2 element|2]]

| {{element cell propproperty|1=Li|145.92 3=136|ffff217=#99ccff|2=lithium |Primordial5=primordial}}

| {{element cell propproperty|1=Be|3=292.40 |ffff217=#99ccff|2=beryllium |Primordial5=primordial}}

| colspan="1011"|<br />|

| {{element cell propproperty|1=B |489.7 3=508 |ffff007=#ffffcc|2=boron |Primordial5=primordial}}

| {{element cell propproperty|1=C |355.8 3=715 |ffff007=#ffffcc|2=carbon |Primordial5=primordial}}

| {{element cell propproperty|1=N |23=5.7928 57|ffff637=#ffccff|2=nitrogen |Primordial5=primordial}}

| {{element cell propproperty|1=O |3=6.409982 |ffff637=#ffccff|2=oxygen |Primordial5=primordial}}

| {{element cell propproperty|1=F |3=6.269862 |ffff637=#ffccff|2=fluorine |Primordial5=primordial}}

| {{element cell propproperty|1=Ne|3=1.732671 |ffff637=#ffccff|2=neon |Primordial5=primordial}}

|-

! [[Period 3 element|3]]

| {{element cell propproperty|1=Na|963=97.96 4|ffff427=#ccffcc|2=sodium |Primordial5=primordial}}

| {{element cell propproperty|1=Mg|127.43=128 |ffff217=#99ccff|2=magnesium |Primordial5=primordial}}

| colspan="1011"|<br />|

| {{element cell propproperty|1=Al|293.43=284 |ffff217=#99ccff|2=aluminium |Primordial5=primordial}}

| {{element cell propproperty|1=Si|384.223=359 |ffff007=#ffffcc|2=silicon |Primordial5=primordial}}

| {{element cell propproperty|1=P |3=12.1294 |ffff427=#ccffcc|2=phosphorus |Primordial5=primordial}}

| {{element cell propproperty|1=S |1.71753=45 |ffff637=#cfc|2=sulfur |Primordial5=primordial}}

| {{element cell propproperty|1=Cl|103=20.2 4|ffff427=#ccffcc|2=chlorine |Primordial5=primordial}}

| {{element cell propproperty|1=Ar|3=6.44753 |ffff637=#ffccff|2=argon |Primordial5=primordial}}

|-

! [[Period 4 element|4]]

| {{element cell propproperty|1=K |793=76.87 9 |ffff427=#ccffcc|2=potassium |Primordial5=primordial}}

| {{element cell propproperty|1=Ca|153.6 3=155 |ffff217=#99ccff|2=calcium |Primordial5=primordial}}

|

| {{element cell prop|Sc|314.2 |ffff00|scandium |Primordial}}

| {{element cell propproperty|Ti1=Sc|421 3=333 |ffff007=#ffffcc|titanium2=scandium |Primordial5=primordial}}

| {{element cell propproperty|V 1=Ti|4523=425 |ffff007=#ffffcc|vanadium2=titanium |Primordial5=primordial}}

| {{element cell propproperty|Cr1=V |344.3=444 |ffff007=#ffffcc|chromium2=vanadium |Primordial5=primordial}}

| {{element cell propproperty|Mn1=Cr|226 3=339|ffff217=#ffffcc|manganese2=chromium |Primordial5=primordial}}

| {{element cell propproperty|Fe1=Mn|349.63=221 |ffff007=#99ccff|iron 2=manganese |Primordial5=primordial}}

| {{element cell propproperty|Co1=Fe|376.5 3=340|ffff007=#ffffcc|cobalt2=iron |Primordial5=primordial}}

| {{element cell propproperty|Ni1=Co|370.4 3=377 |ffff007=#ffffcc|nickel2=cobalt |Primordial5=primordial}}

| {{element cell propproperty|Cu1=Ni|300.3 =379|ffff007=#ffffcc|copper2=nickel |Primordial5=primordial}}

| {{element cell propproperty|Zn1=Cu|115.3 =300|ffff217=#ffffcc|zinc 2=copper |Primordial5=primordial}}

| {{element cell propproperty|Ga1=Zn|3=115|258.7=#99ccff|2=zinc |ffff21|gallium |Primordial5=primordial}}

| {{element cell propproperty|Ge1=Ga|330.9 3=256 |ffff007=#99ccff|germanium2=gallium |Primordial5=primordial}}

| {{element cell propproperty|As1=Ge|34.76 3=334 |ffff427=#ffffcc|arsenic 2=germanium |Primordial5=primordial}}

| {{element cell propproperty|Se1=As|263=32.3 4 |ffff427=#ccffcc|selenium2=arsenic |Primordial5=primordial}}

| {{element cell propproperty|Br1=Se|153=95.4385 |ffff427=#ccffcc|bromine 2=selenium |Primordial5=primordial}}

| {{element cell propproperty|Kr1=Br|93=30.029 0 |ffff637=#ccffcc|krypton2=bromine |Primordial5=primordial}}

| {{element cell property|1=Kr|3=9.08 |7=#ffccff|2=krypton |5=primordial}}

|-

! [[Period 5 element|5]]

| {{element cell propproperty|1=Rb|723=75.216 8|ffff427=#ccffcc|2=rubidium |Primordial5=primordial}}

| {{element cell propproperty|1=Sr|1443=141 |ffff217=#99ccff|2=strontium |Primordial5=primordial}}

|

| {{element cell prop|Y |363 |ffff00|yttrium |Primordial}}

| {{element cell propproperty|Zr1=Y |58.23=390 |ffff007=#ffffcc|zirconium2=yttrium |Primordial5=primordial}}

| {{element cell propproperty|Nb1=Zr|696.6 3=573 |ffff007=#ffffcc|niobium 2=zirconium |Primordial5=primordial}}

| {{element cell propproperty|Mo1=Nb|5983=690 |7=#ffffcc|2=niobium |ffff00|molybdenum |Primordial5=primordial}}

| {{element cell propproperty|Tc1=Mo|6603=617 |ffff007=#ffffcc|technetium2=molybdenum |Synthetic5=primordial}}

| {{element cell propproperty|Ru1=Tc|5953=585 |ffff007=#ffffcc|ruthenium 2=technetium |Primordial5=from decay}}

| {{element cell propproperty|Rh1=Ru|4933=619 |ffff007=#ffffcc|rhodium 2=ruthenium |Primordial5=primordial}}

| {{element cell propproperty|Pd1=Rh|3573=494 |ffff007=#ffffcc|palladium2=rhodium |Primordial5=primordial}}

| {{element cell propproperty|Ag1=Pd|250.583=358 |ffff21|silver |7=#ffffcc|2=palladium |Primordial5=primordial}}

| {{element cell propproperty|Cd1=Ag|100 3=254|ffff217=#99ccff|cadmium2=silver |Primordial5=primordial}}

| {{element cell propproperty|In1=Cd|2313=99.59 |ffff217=#cfc|indium 2=cadmium |Primordial5=primordial}}

| {{element cell propproperty|Sn1=In|295.8 3=232 |ffff217=#99ccff|tin 2=indium |Primordial5=primordial}}

| {{element cell propproperty|Sb1=Sn|77.14 3=296 |ffff427=#99ccff|antimony2=tin |Primordial5=primordial}}

| {{element cell propproperty|Te1=Sb|52.553=193 |ffff427=#9cf|tellurium2=antimony |Primordial5=primordial}}

| {{element cell propproperty|I 1=Te|20.7523=114 |ffff427=#9cf|iodine 2=tellurium |Primordial5=primordial}}

| {{element cell propproperty|Xe1=I |123=41.6366 |ffff427=#ccffcc|xenon 2=iodine |Primordial5=primordial}}

| {{element cell property|1=Xe|3=12.6 |7=#ccffcc|2=xenon |5=primordial}}

|-

! [[Period 6 element|6]]

| {{element cell propproperty|1=Cs|673=63.74 9 |ffff427=#ccffcc|2=caesium |Primordial5=primordial}}

| {{element cell propproperty|1=Ba|1423=140 |ffff217=#99ccff|2=barium |Primordial5=primordial}}

| {{element cell prop-asterisk|* | |ffffff|Lanthanides |Undiscovered1}}

| {{element cell propproperty|Hf1=Lu|575 3=414|ffff007=#ffc|hafnium 2=lutetium |Primordial5=primordial}}

| {{element cell propproperty|Ta1=Hf|7433=648 |ffff007=#ffffcc|tantalum2=hafnium |Primordial5=primordial}}

| {{element cell propproperty|W 1=Ta|8243=733 |ffff007=#ffffcc|tungsten2=tantalum |Primordial5=primordial}}

| {{element cell propproperty|Re1=W |7153=807 |ffff007=#ffffcc|rhenium 2=tungsten |Primordial5=primordial}}

| {{element cell propproperty|Os1=Re|627.63=704 |ffff007=#ffffcc|osmium 2=rhenium |Primordial5=primordial}}

| {{element cell propproperty|Ir1=Os|604 3=678|ffff007=#ffffcc|iridium2=osmium |Primordial5=primordial}}

| {{element cell propproperty|Pt1=Ir|5103=564 |ffff007=#ffffcc|platinum2=iridium |Primordial5=primordial}}

| {{element cell propproperty|Au1=Pt|334.43=510 |ffff007=#ffffcc|gold 2=platinum |Primordial5=primordial}}

| {{element cell propproperty|Hg1=Au|59.2293=342 |ffff427=#ffffcc|mercury2=gold (element)|Primordial|mercury (element) |5=primordial}}

| {{element cell propproperty|Tl1=Hg|1643=59.1 |7=#ccffcc|2=mercury (element)|ffff215=primordial|thallium6=Mercury |Primordial(element)}}

| {{element cell propproperty|Pb1=Tl|3=165|177.7 =#99ccff|ffff21|lead 2=thallium |Primordial5=primordial}}

| {{element cell propproperty|Bi1=Pb|104.8 3=179 |ffff217=#99ccff|bismuth2=lead |Primordial5=primordial}}

| {{element cell propproperty|Po1=Bi|60.1 3=179 |ffff427=#99ccff|polonium2=bismuth |Natural radio|5=primordial}}

| {{element cell propproperty|At1=Po|114 3=103 |ffff217=#9cf|astatine2=polonium |Natural5=from radiodecay}}

| {{element cell propproperty|Rn1=At|163=54.4 |ffff427=#ccffcc|radon 2=astatine |Natural5=from radiodecay}}

| {{element cell property|1=Rn|3=18.1 |7=#ccffcc|2=radon |5=from decay}}

|-

! [[Period 7 element|7]]

| {{element cell propproperty|1=Fr|''n/a''3=65|ccccff7=#cfc|2=francium |Natural5=from radiodecay}}

| {{element cell propproperty|1=Ra|373=113 |ffff427=#9cf|2=radium |Natural5=from radiodecay}}

| {{element cell prop-asterisk|**| |ffffff|Actinides |Undiscovered2vert}}

| {{element cell propproperty|Rf1=Lr|3=''n/a''|7=#ffffff|rutherfordium2=lawrencium |Synthetic5=synthetic}}

| {{element cell propproperty|Db1=Rf|3=''n/a''|7=#ffffff|dubnium 2=rutherfordium |Synthetic5=synthetic}}

| {{element cell propproperty|Sg1=Db|3=''n/a''|7=#ffffff|seaborgium2=dubnium |Synthetic5=synthetic}}

| {{element cell propproperty|Bh1=Sg|3=''n/a''|7=#ffffff|bohrium 2=seaborgium |Synthetic5=synthetic}}

| {{element cell propproperty|Hs1=Bh|3=''n/a''|7=#ffffff|hassium2=bohrium |Synthetic5=synthetic}}

| {{element cell propproperty|Mt1=Hs|3=''n/a''|7=#ffffff|meitnerium2=hassium |Synthetic5=synthetic}}

| {{element cell propproperty|Ds1=Mt|3=''n/a''|7=#ffffff|darmstadtium2=meitnerium |Synthetic5=synthetic}}

| {{element cell propproperty|Rg1=Ds|3=''n/a''|7=#ffffff|roentgenium 2=darmstadtium |Synthetic5=synthetic}}

| {{element cell propproperty|Uub1=Rg|3=''n/a''|7=#ffffff|ununbium 2=roentgenium |Synthetic5=synthetic}}

| {{element cell propproperty|Uut1=Cn|3=''n/a''|7=#ffffff|ununtrium 2=copernicium |Synthetic5=synthetic}}

| {{element cell propproperty|Uuq1=Nh|3=''n/a''|7=#ffffff|ununquadium2=nihonium |Synthetic5=synthetic}}

| {{element cell propproperty|Uup1=Fl|3=''n/a''|7=#ffffff|ununpentium2=flerovium |Synthetic5=synthetic}}

| {{element cell propproperty|Uuh1=Mc|3=''n/a''|7=#ffffff|ununhexium 2=moscovium |Synthetic5=synthetic}}

| {{element cell propproperty|Uus1=Lv|3=''n/a''|7=#ffffff|ununseptium2=livermorium |Undiscovered5=synthetic}}

| {{element cell propproperty|Uuo1=Ts|3=''n/a''|7=#ffffff|ununoctium 2=tennessine |Undiscovered5=synthetic}}

| {{element cell property|1=Og|3=''n/a''|7=#ffffff|2=oganesson |5=synthetic}}

|-

| colspan="21"|<br />

|-

| colspan="4" style="text{{element cell-asterisk|1|align:=right"|* '''[[Lanthanide]]s'''}}

| {{element cell propproperty|1=La|4143=400 |ffff007=#ffffcc|2=lanthanum |Primordial5=primordial}}

| {{element cell propproperty|1=Ce|4143=398 |ffff007=#ffffcc|2=cerium |Primordial5=primordial}}

| {{element cell propproperty|1=Pr|''n/a''3=331|ffffff7=#ffc|2=praseodymium |Primordial5=primordial}}

| {{element cell propproperty|1=Nd|''n/a''3=289|ffffff7=#9cf|2=neodymium |Primordial5=primordial}}

| {{element cell propproperty|1=Pm|''n/a''3=289|ffffff7=#9cf|2=promethium |Synthetic5=from decay}}

| {{element cell propproperty|1=Sm|''n/a''3=172|ffffff7=#9cf|2=samarium |Primordial5=primordial}}

| {{element cell propproperty|1=Eu|''n/a''3=176|ffffff7=#9cf|2=europium |Primordial5=primordial}}

| {{element cell propproperty|1=Gd|''n/a''3=301|ffffff7=#ffc|2=gadolinium |Primordial5=primordial}}

| {{element cell propproperty|1=Tb|''n/a''3=391|ffffff7=#ffc|2=terbium |Primordial5=primordial}}

| {{element cell propproperty|1=Dy|''n/a''3=280|ffffff7=#9cf|2=dysprosium |Primordial5=primordial}}

| {{element cell propproperty|1=Ho|''n/a''3=251|ffffff7=#9cf|2=holmium |Primordial5=primordial}}

| {{element cell propproperty|1=Er|''n/a''3=280|ffffff7=#9cf|2=erbium |Primordial5=primordial}}

| {{element cell propproperty|1=Tm|''n/a''3=191|ffffff7=#9cf|2=thulium |Primordial5=primordial}}

| {{element cell propproperty|1=Yb|''n/a''3=129|ffffff7=#9cf|2=ytterbium |Primordial5=primordial}}

| {{element cell prop|Lu|''n/a''|ffffff|lutetium |Primordial}}

|-

| colspan="4" style="text{{element cell-asterisk|2vert|align:=right"|** '''[[Actinide]]s'''}}

| {{element cell propproperty|1=Ac|''n/a''3=400|ffffff7=#ffc|2=actinium |Natural5=from radiodecay}}

| {{element cell propproperty|1=Th|3=514.4 |ffff007=#ffffcc|2=thorium |Primordial5=primordial}}

| {{element cell propproperty|1=Pa|''n/a''3=481|ffffff7=#ffc|2=protactinium |Natural5=from radiodecay}}

| {{element cell propproperty|1=U |''n/a''3=417|ffffff7=#ffc|2=uranium |Primordial5=primordial}}

| {{element cell propproperty|1=Np|''n/a''3=336|ffffff7=#ffc|2=neptunium |Synthetic5=from decay}}

| {{element cell propproperty|1=Pu|''n/a''3=333|ffffff7=#ffc|2=plutonium |Synthetic5=from decay}}

| {{element cell propproperty|1=Am|3=''n/a''|7=#ffffff|2=americium |Synthetic5=synthetic}}

| {{element cell propproperty|1=Cm|3=''n/a''|7=#ffffff|2=curium |Synthetic5=synthetic}}

| {{element cell propproperty|1=Bk|3=''n/a''|7=#ffffff|2=berkelium |Synthetic5=synthetic}}

| {{element cell propproperty|1=Cf|3=''n/a''|7=#ffffff|2=californium |Synthetic5=synthetic}}

| {{element cell propproperty|1=Es|3=''n/a''|7=#ffffff|2=einsteinium |Synthetic5=synthetic}}

| {{element cell propproperty|1=Fm|3=''n/a''|7=#ffffff|2=fermium |Synthetic5=synthetic}}

| {{element cell propproperty|1=Md|3=''n/a''|7=#ffffff|2=mendelevium |Synthetic5=synthetic}}

| {{element cell propproperty|1=No|3=''n/a''|7=#ffffff|2=nobelium |Synthetic5=synthetic}}

|-

| {{element cell prop|Lr|''n/a''|ffffff|lawrencium |Synthetic}}

| &nbsp;

|}

|-

|

| colspan=20 | Enthalpy in kJ/mol, measured at their respective normal boiling points

|- style="height:2em; border:1px solid grey; text-align:center;"

|

| colspan=3 style="background:#ffccff;" | 0&ndash;10 kJ/mol

| colspan=3 style="background:#ccffcc;" | 10&ndash;100 kJ/mol

| colspan=3 style="background:#99ccff;" | 100&ndash;300 kJ/mol

| colspan=3 style="background:#ffffcc;" | >300 kJ/mol

|}</div></div>

The vaporization of metals is a key step in [[metal vapor synthesis]], which exploits the increased reactivity of metal atoms or small particles relative to the bulk elements.

===Other common substances===

{| border="2" cellpadding="4" style="background:silver; border:1px solid gray; border-collapse:collapse; margin:0 1em 1em 0; text-align:center; {{{1|}}}"

Enthalpies of vaporization of common substances, measured at their respective standard boiling points:

{| class="wikitable sortable"

! rowspan=2 | Compound

! colspan=3 | Boiling point, at normal pressure

! colspan=2 | Heat of vaporization

|-

! (K)

! (°C)

! (°F)

! ([[kilojoule per mole|kJ/mol]])

! (J/g)

|-

| [[Acetone]]

| 329 || 56 || 133

| 31.300

| 538.9

|-

| [[Aluminium]]

| 2792 || 2519 || 4566

| 294.0

| 10500

|-

| [[Ammonia]]

| 240 || −33.34 || −28

| 23.35

| 1371

|-

| [[Butane]]

| 272–274 || −1 || 30–34

| 21.0

| 320

|-

| [[Diethyl ether]]

| 307.8 || 34.6 || 94.3

| 26.17

| 353.1

|-

| [[Ethanol]]

| 352 || 78.37 || 173

| 38.6

| 841

|-

| [[Hydrogen]] ([[parahydrogen]])

| 20.271 || −252.879 || −423.182

| 0.8992

| 446.1

|-

| [[Iron]]

| 3134 || 2862 || 5182

| 340

| 6090

|-

| [[Isopropyl alcohol]]

| 356 || 82.6 || 181

| 44

| 732.2

|-

| [[Methane]]

| 112 || −161 || −259

| 8.170

| 480.6

|-

| [[Methanol]]

| 338 || 64.7 || 148

| 35.2<ref>NIST</ref>

| 1104

|-

| [[Propane]]

|+ '''Standard enthalpy change of vaporization at 298 K'''

| 231 || −42 || −44

| 15.7

| 356

|-

| [[Phosphine]]

| style="background:ffff63;" width="20%" | 0&ndash;10 kJ/mol

| 185 || −87.7 || −126

| style="background:ffff42;" width="20%" | 10&ndash;100 kJ/mol

| 14.6

| style="background:ffff21;" width="20%" | 100&ndash;300 kJ/mol

| 429.4

| style="background:ffff00;" width="20%" | >300 kJ/mol

|-

| [[Properties of water|Water]]

| 373.15 || 100 || 212

| 40.66

| 2257

|}

</center>

===Other common substances===

<table border="0" cellpadding="0" cellspacing="0">

<tr><td align="top"><table border="1" cellpadding="2" cellspacing="0">

<tr><th>'''Element'''</th><th>'''Heat of vaporization ([[Kilojoule per mole|kJ/mol]])'''</th></tr>

<tr><td>[[Methanol]]</td><td>37.4</td></tr>

<tr><td>[[Ammonia]]</td><td>23.35</td></tr>

<tr><td>[[Water]]</td><td>40.65</td></tr>

<tr><td>[[Methane]]</td><td>8.19</td></tr>

<tr><td>[[Phosphine]]</td><td>14.6</tr>

<tr><td>[[Propane]]</td><td>356 kJ/kg</td></tr>

<tr><td>[[Butane]]</td><td>362 kJ/kg</td></tr>

</td></tr>

</table>

==See also==

*[[Clausius–Clapeyron relation]]

*[[Standard enthalpy change of fusion]]

*[[Shimansky equation]], describes the temperature dependence of the heat of vaporization

*[[Enthalpy of fusion]], specific heat of melting

*[[Enthalpy of sublimation]]

*[[Joback method]], estimation of the heat of vaporization at the normal boiling point from molecular structures

*[[Latent heat]]

==ReferenceReferences==

{{Reflist}}

Sears, Zemansky et. al., University Physics, Addison-Wessley Publishing Company, Sixth ed., 1982, ISBN 0-201-07199-1

*[http://www.codata.info/resources/databases/key1.html CODATA Key Values for Thermodynamics]

*{{cite book|last1=Gmelin|first1=Leopold|title=Gmelin-Handbuch der anorganischen Chemie / 08 a|date=1985|publisher=Springer|___location=Berlin [u.a.]|isbn=978-3-540-93516-2|pages=116–117|edition=8., völlig neu bearb. Aufl.}}

*[http://webbook.nist.gov/chemistry/ NIST Chemistry WebBook]

*{{cite book|last1=Young|first1=Francis W. Sears, Mark W. Zemansky, Hugh D.|title=University physics|date=1982|publisher=Addison-Wesley|___location=Reading, Mass.|isbn=978-0-201-07199-3|edition=6th}}

{{States of matter}}

[[Category:Chemical properties]]

{{Authority control}}

[[Category:Thermodynamics]]

[[Category:Heat]]

{{DEFAULTSORT:Enthalpy Of Vaporization}}

[[af:Verdampingswarmte]]

[[Category:Enthalpy]]

[[ar:حرارة تبخر]]

[[ca:Calor de vaporització]]

[[cs:Měrné skupenské teplo varu]]

[[de:Verdampfungswärme]]

[[es:Entalpía de vaporización]]

[[fr:Énergie de vaporisation]]

[[ko:기화열]]

[[lt:Garavimo šiluma]]

[[nl:Verdampingswarmte]]

[[pl:Ciepło parowania]]

[[pt:Entalpia de vaporização]]

[[sl:Izparilna toplota]]

[[sr:Топлота испаравања]]

[[sv:Ångbildningsvärme]]

[[th:ความร้อนแฝงของการกลายเป็นไอ]]

[[zh:汽化热]]