ASTM E2071-00(2015)

Standard Practice for Calculating Heat of Vaporization or Sublimation from Vapor Pressure Data

ABSTRACT
This practice describes the calculation of the heat of vaporization of a liquid or the heat of sublimation of a solid from measured vapor pressure data. It is applicable to pure liquids, azeotropes, pure solids, and homogenous solid solutions over the temperature range for which the vapor pressure equation fitted to the measured data is applicable. Vapor pressure data shall be measured in accordance to the test methods and shall be correlated with the Antoine equation. The heat of vaporization or sublimation is computed at the desired temperature from the vapor-pressure temperature derivative from the fitted Antoine equation by use of the Clapeyron equation.
SCOPE
1.1 This practice describes the calculation of the heat of vaporization of a liquid or the heat of sublimation of a solid from measured vapor pressure data. It is applicable to pure liquids, azeotropes, pure solids, and homogenous solid solutions over the temperature range for which the vapor pressure equation fitted to the measured data is applicable.  
Note 1: This practice is generally not applicable to liquid mixtures. For a pure liquid or azeotrope, composition does not change upon vaporization so that the integral heat of vaporization is identical to the differential heat of vaporization. Non-azeotropic liquid mixtures change composition upon vaporizing. Heat of vaporization data computed from this practice for a liquid mixture are valid only as an approximation to the mixture differential heat of vaporization; it is not a valid approximation to the mixture integral heat of vaporization.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 There is no ISO standard equivalent to this practice.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2015
• ICS: 27.040 - Gas and steam turbines. Steam engines
• Technical Committee: E37 - Thermal Measurements
• Drafting Committee: E37.10 - Fundamental, Statistical and Mechanical Properties

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E2071 − 00 (Reapproved 2015)
Standard Practice for
Calculating Heat of Vaporization or Sublimation from Vapor
1
Pressure Data
This standard is issued under the fixed designation E2071; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
3
1. Scope E1194 Test Method for Vapor Pressure (Withdrawn 2013)
E1719 Test Method for Vapor Pressure of Liquids by Ebul-
1.1 This practice describes the calculation of the heat of
liometry
vaporization of a liquid or the heat of sublimation of a solid
E1782 Test Method for Determining Vapor Pressure by
from measured vapor pressure data. It is applicable to pure
Thermal Analysis
liquids, azeotropes, pure solids, and homogenous solid solu-
tions over the temperature range for which the vapor pressure
3. Terminology
equation fitted to the measured data is applicable.
3.1 Symbols:
NOTE 1—This practice is generally not applicable to liquid mixtures.
3.1.1 A, B, C—Antoine vapor pressure equation constants
For a pure liquid or azeotrope, composition does not change upon
(log , kPa, K), Antoine vapor pressure equation:
10
vaporization so that the integral heat of vaporization is identical to the
differential heat of vaporization. Non-azeotropic liquid mixtures change
log P 5 A 2 B/ T1C
~ !
10
composition upon vaporizing. Heat of vaporization data computed from
3.1.2 P—vapor pressure, kPa.
this practice for a liquid mixture are valid only as an approximation to the
mixture differential heat of vaporization; it is not a valid approximation to
3.1.3 P —critical pressure, kPa.
c
the mixture integral heat of vaporization.
3.1.4 P —reduced pressure = P/P .
r c
1.2 The values stated in SI units are to be regarded as
3.1.5 T—absolute temperature, K.
standard. No other units of measurement are included in this
3.1.6 T —critical temperature, K.
c
standard.
3.1.7 T —reduced temperature = T/T .
r c
1.3 There is no ISO standard equivalent to this practice.
3
3.1.8 V—molar volume, cm /mol.
1.4 This standard does not purport to address all of the
3
3.1.9 R—gas constant, 8.31433 J/mol-K; 8314330 kPa-cm /
safety concerns, if any, associated with its use. It is the
mol-K.
responsibility of the user of this standard to establish appro-
3.1.10 ∆H —heat of vaporization, J/mol.
priate safety and health practices and determine the applica-
V
bility of regulatory limitations prior to use.
3.1.11 ∆Z —difference in compressibility factor (Z = PV/
V
RT) upon vaporization. Clapeyron equation:
2. Referenced Documents
∆H 52R∆Z @d~lnP!/d~1/T!#
V V
2
2.1 ASTM Standards: 3.1.11.1 Discussion—The subscript “V” will be used
D2879 Test Method for Vapor Pressure-Temperature Rela- throughout this practice to designate the vaporization of a
tionship and Initial Decomposition Temperature of Liq- liquid. If the vapor pressure data were measured for a solid,
uids by Isoteniscope substitute the subscript “S” for the sublimation of a solid.
E1142 Terminology Relating to Thermophysical Properties
3.2 Definitions:
3.2.1 Specialized terms used in this practice are defined in
Terminology E1142.
1
This practice is under the jurisdiction of Committee E37 on Thermal Measure- 3.2.2 sublimation—transition from a solid phase to a gas-
ments and is the direct responsibility of Subcommittee E37.10 on Fundamental,
eous phase.
Statistical and Mechanical Properties.
3.2.3 vaporization—transition from a liquid phase to a
Current edition approved May 1, 2015. Published May 2015. Originally
approved in 2000. Last previous edition approved in 2010 as E2071 – 00 (2010).
gaseous phase.
DOI: 510.1520/E2071-00R15.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E2071 − 00 (2015)
4. Summary of Practice 7. Calculation
7.1 At each temperature of interest, calculate the vapor
4.1 Vapor pressure data are measured by other referenced
pressure from the Antoine equation and calculate the vapor-
ASTM standards and then correlated with the Antoine equa-
pressure temperature derivative from the fitted Antoine equa-
tion.Theheatofvaporizationorsublimationiscomputedatthe
tion constants from:
desired temperature from the vapor-pressure temperature de-
2 2
d lnP /d 1/T 522.3025851 BT / T1C
@ ~ ! ~
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2071 − 00 (Reapproved 2010) E2071 − 00 (Reapproved 2015)
Standard Practice for
Calculating Heat of Vaporization or Sublimation from Vapor
1
Pressure Data
This standard is issued under the fixed designation E2071; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice describes the calculation of the heat of vaporization of a liquid or the heat of sublimation of a solid from
measured vapor pressure data. It is applicable to pure liquids, azeotropes, pure solids, and homogenous solid solutions over the
temperature range for which the vapor pressure equation fitted to the measured data is applicable.
NOTE 1—This practice is generally not applicable to liquid mixtures. For a pure liquid or azeotrope, composition does not change upon vaporization
so that the integral heat of vaporization is identical to the differential heat of vaporization. Non-azeotropic liquid mixtures change composition upon
vaporizing. Heat of vaporization data computed from this practice for a liquid mixture are valid only as an approximation to the mixture differential heat
of vaporization; it is not a valid approximation to the mixture integral heat of vaporization.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 There is no ISO standard equivalent to this practice.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
D2879 Test Method for Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature of Liquids by
Isoteniscope
E1142 Terminology Relating to Thermophysical Properties
3
E1194 Test Method for Vapor Pressure (Withdrawn 2013)
E1719 Test Method for Vapor Pressure of Liquids by Ebulliometry
E1782 Test Method for Determining Vapor Pressure by Thermal Analysis
3. Terminology
3.1 Symbols:
3.1.1 A, B, C—Antoine vapor pressure equation constants (log , kPa, K), Antoine vapor pressure equation:
10
log P 5 A 2 B/ T1C
~ !
10
3.1.2 P—vapor pressure, kPa.
3.1.3 P —critical pressure, kPa.
c
3.1.4 P —reduced pressure = P/P .
r c
3.1.5 T—absolute temperature, K.
3.1.6 T —critical temperature, K.
c
3.1.7 T —reduced temperature = T/T .
r c
1
This practice is under the jurisdiction of Committee E37 on Thermal Measurements and is the direct responsibility of Subcommittee E37.10 on Fundamental, Statistical
and Mechanical Properties.
Current edition approved July 1, 2010May 1, 2015. Published August 2010May 2015. Originally approved in 2000. Last previous edition approved in 20002010 as
E2071 – 00 (2005).(2010). DOI: 510.1520/E2071-00R10.510.1520/E2071-00R15.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E2071 − 00 (2015)
3
3.1.8 V—molar volume, cm /mol.
3
3.1.9 R—gas constant, 8.31433 J/mol-K; 8314330 kPa-cm /mol-K.
3.1.10 ΔH —heat of vaporization, J/mol.
V
3.1.11 ΔZ —difference in compressibility factor (Z = PV/RT) upon vaporization. Clapeyron equation:
V
ΔH 52RΔZ d lnP /d 1/T
@ ~ ! ~ !#
V V
3.1.11.1 Discussion—
The subscript “V” will be used throughout this practice to designate the vaporization of a liquid. If the vapor pressure data were
measured for a solid, substitute the subscript “S” for the sublimation of a solid.
3.2 Definitions:
3.2.1 Specialized terms used in this practice are defined in Terminology E1142.
3.2.2 sublimation—transition from a solid phase to a gaseous phase.
3.2.3 vaporization—transition from a liquid phase to a gaseous phase.
4. Summary of Practice
4.1 Vapor pressure data are measured by other referenced ASTM Standardsstandards and then correlated with the Antoine
equation. The hea
...