EN ISO 80000-9:2013

SLOVENSKI STANDARD
01-junij-2013
1DGRPHãþD
SIST ISO 31-8:1995/Amd.1:2001
SIST ISO 31-8+A1:2008
9HOLþLQHLQHQRWHGHO)L]LNDOQDNHPLMDLQPROHNXOVNDIL]LND,62
$PG
Quantities and units - Part 9: Physical chemistry and molecular physics (ISO 80000-
9:2009 + Amd 1:2011)
Größen und Einheiten - Teil 9: Physikalische Chemie und Molekularphysik (ISO 80000-
9:2009 + Amd 1:2011)
Grandeurs et unités - Partie 9: Chimie physique et physique moléculaire (ISO 80000-
9:2009 + Amd 1:2011)
Ta slovenski standard je istoveten z: EN ISO 80000-9:2013
ICS:
01.060 9HOLþLQHLQHQRWH Quantities and units
07.030 Fizika. Kemija Physics. Chemistry
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 80000-9
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2013
ICS 01.060
English Version
Quantities and units - Part 9: Physical chemistry and molecular
physics (ISO 80000-9:2009 + Amd 1:2011)
Grandeurs et unités - Partie 9: Chimie physique et Größen und Einheiten - Teil 9: Physikalische Chemie und
physique moléculaire (ISO 80000-9:2009 + Amd 1:2011) Molekularphysik (ISO 80000-9:2009 + Amd 1:2011)
This European Standard was approved by CEN on 14 March 2013.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 80000-9:2013: E
worldwide for CEN national Members.

Contents Page
Foreword . 3

Foreword
The text of ISO 80000-9:2009 + Amd 1:2011 has been prepared by Technical Committee ISO/TC 12
“Quantities and units” of the International Organization for Standardization (ISO) and has been taken over as
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by October 2013, and conflicting national standards shall be withdrawn at
the latest by October 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 80000-9:2009 + Amd 1:2011 has been approved by CEN as EN ISO 80000-9:2013 without
any modification.
INTERNATIONAL ISO
STANDARD 80000-9
First edition
2009-04-01
Quantities and units —
Part 9:
Physical chemistry and molecular
physics
Grandeurs et unités —
Partie 9: Chimie physique et physique moléculaire

Reference number
ISO 80000-9:2009(E)
©
ISO 2009
ISO 80000-9:2009(E)
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©
ii ISO 2009 – All rights reserved

ISO 80000-9:2009(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Names, symbols, and definitions . 1
Annex A (normative) Atomic numbers, names, and symbols for the chemical . 32
Annex B (normative) Symbols for chemical elements and nuclides . 34
Annex C (normative) pH . 35
Bibliography . 37
©
ISO 2009 – All rights reserved iii

ISO 80000-9:2009(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 80000-9 was prepared by Technical Committee ISO/TC 12, Quantities and units.
This first edition of ISO 80000-9 cancels and replaces ISO 31-8:1992. It also incorporates the Amendment
ISO 31-8:1992/Amd.1:1998. The major technical changes from the previous standard are the following:
— the presentation of Numerical statements has been changed;
— the Normative references have been changed;
— some new items have been introduced;
— some new chemical elements have been introduced in Annex A;
— Annex C on pH has been revised and given a completely new text.
ISO 80000 consists of the following parts, under the general title Quantities and units:
— Part 1: General
— Part 2: Mathematical signs and symbols to be used in the natural sciences and technology
— Part 3: Space and time
— Part 4: Mechanics
— Part 5: Thermodynamics
— Part 7: Light
— Part 8: Acoustics
— Part 9: Physical chemistry and molecular physics
— Part 10: Atomic and nuclear physics
— Part 11: Characteristic numbers
— Part 12: Solid state physics
IEC 80000 consists of the following parts, under the general title Quantities and units:
— Part 6: Electromagnetism
— Part 13: Information science and technology
— Part 14: Telebiometrics related to human physiology
©
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ISO 80000-9:2009(E)
Introduction
0.1 Arrangements of the tables
The tables of quantities and units in this International Standard are arranged so that the quantities are
presented on the left-hand pages and the units on the corresponding right-hand pages.
All units between two full lines on the right-hand pages belong to the quantities between the corresponding full
lines on the left-hand pages.
Where the numbering of an item has been changed in the revision of a part of ISO 31, the number in the
preceding edition is shown in parentheses on the left-hand page under the new number for the quantity; a dash
is used to indicate that the item in question did not appear in the preceding edition.
0.2 Tables of quantities
The names in English and in French of the most important quantities within the field of this International
Standard are given together with their symbols and, in most cases, their definitions. These names and symbols
are recommendations. The definitions are given for identification of the quantities in the International System of
Quantities (ISQ), listed on the left-hand pages of the table; they are not intended to be complete.
The scalar, vectorial or tensorial character of quantities is pointed out, especially when this is needed for the
definitions.
In most cases only one name and only one symbol for the quantity are given; where two or more names or two
or more symbols are given for one quantity and no special distinction is made, they are on an equal footing.
When two types of italic letters exist (for example as with ϑ and θ; ϕ and φ; a and a; g and g) only one of these
is given. This does not mean that the other is not equally acceptable. It is recommended that such variants
should not be given different meanings. A symbol within parentheses implies that it is a reserve symbol, to be
used when, in a particular context, the main symbol is in use with a different meaning.
In this English edition, the quantity names in French are printed in an italic font, and are preceded by fr. The
gender of the French name is indicated by (m) for masculine and (f) for feminine, immediately after the noun in
the French name.
0.3 Tables of units
0.3.1 General
The names of units for the corresponding quantities are given together with the international symbols and the
definitions. These unit names are language-dependent, but the symbols are international and the same in all
1)
languages. For further information, see the SI Brochure (8th edition 2006) from BIPM and ISO 80000-1 .
The units are arranged in the following way:
a) The coherent SI units are given first. The SI units have been adopted by the General Conference on
Weights and Measures (Conférence Générale des Poids et Mesures, CGPM). The use of coherent SI units
1) To be published.
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ISO 2009 – All rights reserved v

ISO 80000-9:2009(E)
is recommended; decimal multiples and submultiples formed with the SI prefixes are recommended, even
though not explicitly mentioned.
b) Some non-SI units are then given, being those accepted by the International Committee for Weights and
Measures (Comité International des Poids et Mesures, CIPM), or by the International Organization of Legal
Metrology (Organisation Internationale de Métrologie Légale, OIML), or by ISO and IEC, for use with the SI.
Such units are separated from the SI units in the item by use of a broken line between the SI units and the
other units.
c) Non-SI units currently accepted by the CIPM for use with the SI are given in small print (smaller than the text
size) in the “Conversion factors and remarks” column.
d) Non-SI units that are not recommended are given only in annexes in some parts of this International
Standard. These annexes are informative, in the first place for the conversion factors, and are not integral
parts of the standard. These deprecated units are arranged in two groups:
1) units in the CGS system with special names;
2) units based on the foot, pound, second, and some other related units.
e) Other non-SI units are given for information, especially regarding the conversion factors, in informative
annexes in some parts of this International Standard.
0.3.2 Remark on units for quantities of dimension one, or dimensionless quantities
The coherent unit for any quantity of dimension one, also called a dimensionless quantity, is the number one,
symbol 1. When the value of such a quantity is expressed, the unit symbol 1 is generally not written out
explicitly.
EXAMPLE 1 Refractive index n = 1,53× 1 = 1,53
Prefixes shall not be used to form multiples or submultiples of this unit. Instead of prefixes, powers of 10 are
recommended.
EXAMPLE 2 Reynolds number Re = 1,32× 10
Considering that plane angle is generally expressed as the ratio of two lengths and solid angle as the ratio of
two areas, in 1995 the CGPM specified that, in the SI, the radian, symbol rad, and steradian, symbol sr, are
dimensionless derived units. This implies that the quantities plane angle and solid angle are considered as
derived quantities of dimension one. The units radian and steradian are thus equal to one; they may either be
omitted, or they may be used in expressions for derived units to facilitate distinction between quantities of
different kinds but having the same dimension.
0.4 Numerical statements in this International Standard
The sign = is used to denote “is exactly equal to”, the sign ≈ is used to denote “is approximately equal to”, and
the sign := is used to denote “is by definition equal to”.
Numerical values of physical quantities that have been experimentally determined always have an associated
measurement uncertainty. This uncertainty should always be specified. In this International Standard, the
magnitude of the uncertainty is represented as in the following example.
EXAMPLE l = 2,347 82(32) m
In this example, l = a(b) m, the numerical value of the uncertainty b indicated in parentheses is assumed to
apply to the last (and least significant) digits of the numerical value a of the length l. This notation is used when
b represents one standard uncertainty (estimated standard deviation) in the last digits of a. The numerical
example given above may be interpreted to mean that the best estimate of the numerical value of the length l
(when l is expressed in the unit metre) is 2,347 82, and that the unknown value of l is believed to lie between
(2,347 82− 0,000 32) m and (2,347 82 + 0,000 32) m with a probability determined by the standard
uncertainty 0,000 32 m and the probability distribution of the values of l.
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ISO 80000-9:2009(E)
0.5 Special remarks
In this part of ISO 80000, symbols for substances are shown as subscripts, for example c , w , p .
B B
B
Generally, it is advisable to put symbols for substances and their states in parentheses on the same line as the
main symbol, for example c(H SO ).
2 4
�
∗
The superscript is used to mean “pure”. The superscript is used to mean “standard”.
−3 ◦
EXAMPLE 1 V (K SO , 0,1 mol· dm in H O, 25 C) for molar volume.
m
2 4 2
� −1 −1
EXAMPLE 2 C (H O, g, 298,15 K) = 33,58 J· K · mol for standard molar heat capacity at constant pressure.
m,p
�
∗ ∗
ln an expression such as ϕ = x V / x V , where ϕ denotes the volume fraction of a particular
B B i B
m,B m,i
substance B in a mixture of substances A, B, C, …, where x denotes the amount-of-substance fraction of i and
i
∗ ∗ ∗ ∗
V the molar volume of the pure substance i, and where all the molar volumes V , V , V , . are taken
m,i m,A m,B m,C
at the same temperature and pressure, the summation on the right-hand side is that over all the substances A,
�
B, C, . of which a mixture is composed, so that x = 1.
i
The names and symbols of the chemical elements are given in Annex A.
Additional qualifying information on a quantity symbol may be added as a subscript or superscript or in
parentheses after the symbol.
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ISO 2009 – All rights reserved vii

.
viii
INTERNATIONAL STANDARD ISO 80000-9:2009(E)
Quantities and units —
Part 9:
Physical chemistry and molecular physics
1Scope
ISO 80000-9 gives names, symbols, and definitions for quantities and units of physical chemistry and molecular
physics. Where appropriate, conversion factors are also given.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 80000-3:2006, Quantities and units — Part 3: Space and time
ISO 80000-4:2006, Quantities and units — Part 4: Mechanics
ISO 80000-5:2007, Quantities and units — Part 5: Thermodynamics
IEC 80000-6:2008, Quantities and units — Part 6: Electromagnetism
3 Names, symbols, and definitions
The names, symbols, and definitions for quantities and units of physical chemistry and molecular physics are
given on the following pages.
©
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ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
9-1 amount of n amount of substance is one of the Amount of substance of a pure
(8-3) substance seven base quantities in the sample is that quantity that can
fr quantité (f) de International System of Quantities, often be determined by
matière ISQ, on which the SI is based measuring its mass and
dividing by the molar mass of
the sample.
Amount of substance is
defined to be proportional to
the number of specified
elementary entities in a
sample, the proportionality
constant being a universal
constant which is the same for
all samples.
The name “number of moles”
is often used for “amount of
substance”, but this is
deprecated because the name
of a quantity should be
distinguished from the name of
the unit.
In the name “amount of
substance”, the words “of
substance” could, for
simplicity, be replaced by
words to specify the substance
concerned in any particular
application, so that one may,
for example, talk of “amount of
hydrogen chloride, HCl”, or
“amount of benzene, C H ”.
6 6
It is important to always give a
precise specification of the
entity involved (as emphasized
in the second sentence of the
definition of the mole); this
should preferably be done by
giving the molecular chemical
formula of the material
involved.
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ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-1.a mole mol the mole is the amount of When the mole is used, the
substance of a system which elementary entities shall be
contains as many elementary specified and may be atoms,
entities as there are atoms in molecules, ions, electrons,
0,012 kg of carbon 12 other entities or specified
groups of them.
[14th CGPM (1971)]
The definition applies to
unbound atoms of carbon 12,
at rest and in their ground
state.
The mole is also used for
entities such as holes and
other quasi-particles, double
bonds, etc.
(continued)
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ISO 2009 – All rights reserved 3

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
A (Cl)≈ 35,453
9-2.1 relative atomic A ratio of the average mass EXAMPLE
r
r
(8-1.1) mass (ISO 80000-4:2006, item 4-1)
The relative atomic or relative
fr masse (f) per atom of an element to 1/12
molecular mass depends on the
atomique of the mass of an atom of the
nuclidic composition.
relative nuclide C
The International Union of Pure
and Applied Chemistry (IUPAC)
9-2.2 relative molecular M ratio of the average mass per
r
accepts the use of the special
(8-1.2) mass molecule or specified entity of a
names “atomic weight” and
fr masse (f) substance to 1/12 of the mass of
“molecular weight” for the
moléculaire an atom of the nuclide C
quantities “relative atomic mass”
relative
and “relative molecular mass”,
respectively. The use of these
traditional names is deprecated.
9-3 number of particles N N equals the number of Different entities may be used as
B B
(8-2) fr nombre (m) particles in a system a particle, e.g. number of
de particules molecules, number of atoms.
A subscript added to the symbol
indicates a specific entity, e.g. N
B
for the number of molecules of
substance B.
9-4 Avogadro constant L, N for a pure sample
A L = 6,022 141 79(30)×
(8-4) fr constante (f)
23 −1 23 −1
10 mol 10 mol
L = N/n
d'Avogadro
[CODATA 2006]
where N is the number of
particles (item 9-3) and n is
amount of substance (item 9-1)
9-5 molar mass M for a pure sample
(8-5) fr masse (f) molaire
M = m/n
where mis mass
(ISO 80000-4:2006, item 4-1)
and n is amount of substance
(item 9-1)
9-6 molar volume V for a pure sample The molar volume of an ideal gas
m
(8-6) fr volume (m) at 273,15 K and 101 325 Pa is
V = V/n
m 3
molaire V = 0,022 413 996 (39) m /mol
m
and, for 273,15 K and 100 000 Pa,
where Vis volume
(ISO 80000-3:2006, item 3-4) the molar volume is
V = 0,022 710 981 (40) m /mol
and n is amount of substance .
m
(item 9-1)
[CODATA 2006]
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ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-2.a one 1 See the Introduction, 0.3.2.
9-3.a one 1 See the Introduction, 0.3.2.
–1
9-4.a mole to the power mol
minus one
9-5.a kilogram per mole kg/mol The commonly used unit for
molar mass is gram per mole,
g/mol, rather than kilogram per
mole, kg/mol.
9-6.a cubic metre per m /mol
mole
(continued)
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ISO 2009 – All rights reserved 5

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
9-7 molar internal U U = U/n Similar definitions apply to
m m
(8-7) energy other thermodynamic
where U is internal energy
fr énergie (f) interne functions, for example molar
(ISO 80000-5:2007, item 5-20.2)
molaire
enthalpy, H , molar Helmholz
m
and n is amount of substance (item
energy, A , and molar Gibbs
m
9-1)
energy, G . These quantities
m
are normally only used with
9-8 molar heat capacity C C = C/n
m m
reference to pure substances.
(8-8) fr capacité (f)
where C is heat capacity
Molar heat capacity may be
thermique
(ISO 80000-5:2007, item 5-15) and
defined at constant pressure,
molaire
n is amount of substance (item
or at constant volume,
C
m,p
9-1)
C .
m,V
9-9 molar entropy S S = S/n
m m
(8-9) fr entropie (f)
where S is entropy
molaire
(ISO 80000-5:2007, item 5-18) and
n is amount of substance (item
9-1)
9-10.1 volumic number of n, (C) n = N/V
(8-10.1) molecules or
where N is the number of particles
other elementary
(item 9-3) and V is volume
entities,
(ISO 80000-3:2006, item 3-4)
number density of
molecules or
other elementary
entities
fr nombre (m)
volumique
de molécules
ou d'autres
entités
élémentaires
9-10.2 molecular C C = N /V
B B B
(8-10.2) concentration of
where N is the number of
B
substance B
molecules of B and V is the
fr concentration (f)
volume (ISO 80000-3:2006, item
moléculaire du
3-4) of the mixture
constituant B
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ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-7.a joule per mole J/mol
9-8.a joule per mole J/(mol · K)
kelvin
9-9.a joule per mole J/(mol · K)
kelvin
–3
9-10.a metre to the power m
minus three
(continued)
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ISO 2009 – All rights reserved 7

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
9-11.1 mass density, ρ, (γ) ρ = m/V
(8-11.1) density
where m is mass
fr masse (f)
(ISO 80000-4:2006, item 4-1) and
volumique
V is volume (ISO 80000-3:2006,
item 3-4)
9-11.2 mass concentration ρ , (γ ) ρ = m /V
B B B B
(8-11.2) of substance B
where m is the mass
B
fr concentration (f)
(ISO 80000-4:2006, item 4-1) of
en masse du
substance B and V is the volume
constituant B
(ISO 80000-3:2006, item 3-4) of
the mixture
9-12 mass fraction of w w = m /m
B B B
(8-12) substance B
where m is the mass
B
fr fraction (f)
(ISO 80000-4:2006, item 4-1) of
massique du
substance B and m is the total
constituant B
mass of the mixture
9-13 amount-of- c c = n /V In chemistry, the name
B B B
(8-13) substance “amount-of-substance
where n is the amount of
B
concentration concentration” is generally
substance (item 9-1) of B and V is
of B abbreviated to the single word
the volume (ISO 80000-3:2006,
fr concentration (f) “concentration”, it being
item 3-4) of the solution
en quantité de assumed that the adjective
matière du “amount-of-substance” is
constituant B intended. For this reason,
however, the word “mass”
should never be omitted from
the name “mass
concentration” in 9-11.2.
The standard concentration,
3 −e
1 mol/dm , is denoted c .
9-14 amount-of- x , y x = n /n For condensed phases, x is
B B B B B
(8-14.1) substance used, and for gaseous
where n is the amount of
B
fraction of B, mixtures y may be used.
B
substance (item 9-1) of B and n is
(mole fraction of
the total amount of substance (item The unsystematic name “mole
substance B)
9-1) in the mixture fraction” is still used. However,
fr fraction (f)
the use of this name is
molaire du
deprecated.
constituant B
For this quantity, the entity
used to define the amount of
substance should always be a
single molecule for every
species in the mixture.
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ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Item No. Name national Definition Conversion factors and remarks
symbol
9-11.a kilogram per cubic kg/m
metre
3 3
9-11.b gram per litre g/l 1 g/l = 1 g/dm = 1 kg/m
9-12.a one 1 See the Introduction, 0.3.2.
9-13.a mole per cubic mol/m
metre
3 3 3
9-13.b mole per litre mol/l 1 mol/l = 1 mol/dm = 10 mol/m
9-14.a one 1 See the Introduction, 0.3.2.
(continued)
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ISO 2009 – All rights reserved 9

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
∗
9-15 volume fraction of ϕ ϕ is temperature-dependent.
B x V B
B
m,B
�
ϕ =
(8-15) substance B B
∗
x V
i
m,i
fr fraction (f)
∗
volumique du
where the V is the molar
m,i
constituant B
volume (item 9-6) of the pure
substances i at the same
temperature and pressure, x
i
denotes the amount-of-substance
fraction (item 9-14) of substance i
and Σ denotes summation over all
substances i
9-16 molality of solute B b , m b = n /m The alternative symbol m
B B B B A B
(8-16) fr molalité (f) du should be avoided in situations
where n is the amount of
B
soluté B where it might be mistaken for
substance (item 9-1) of solute B
the mass of substance B.
and m is the mass
A
(ISO 80000-4:2006, item 4-1) of However, the symbol m is
the solvent substance A much more commonly used
than the symbol b for molality,
despite the possible confusion
with mass.
9-17 chemical potential µ for a mixture of substances i For a pure substance,
B
(8-17) of substance B
µ = G/n = G
m
µ = (∂G/∂n )
B B T ,p,n
i
fr potentiel (m)
G
where is the molar Gibbs
m
chimique du where G is Gibbs energy
energy. In a mixture, µ is the
B
constituant B
(ISO 80000-5:2007, item 5-20.5)
partial molar Gibbs energy.
and n is the amount of substance
B
B (item 9-1)
9-18 absolute activity of λ λ = exp(µ /RT)
B B B
(8-18) substance B
where µ is the chemical potential
B
fr activité (f)
of substance B (item 9-17), R is
absolue du
the molar gas constant (item 9-42),
constituant B
and T is thermodynamic
temperature (ISO 80000-5:2007,
item 5-1)
9-19 partial pressure of for a gaseous mixture,
p
B
(8-19) substance B
p = x · p
B B
fr pression (f)
partielle du where x is the amount-of-
B
constituant B substance fraction of substance B
p
(item 9-14) and is the total
pressure (ISO 80000-4:2006, item
4-15.1)
©
10 ISO 2009 – All rights reserved

ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-15.a one 1 See the Introduction, 0.3.2.
9-16.a mole per kilogram mol/kg
9-17.a joule per mole J/mol
9-18.a one 1 See the Introduction, 0.3.2.
9-19.a pascal Pa
(continued)
©
ISO 2009 – All rights reserved 11

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
9-20 fugacity of p˜ , (f ) for a gaseous mixture, p˜ is p˜ = λ · lim (p /λ )
B B B B B B B
p→0
(8-20) substance B in a proportional to the absolute activity,
gaseous mixture λ (item 9-18), the proportionality where p is total pressure.
B
fr fugacité (f) du factor, which is a function of
constituant B temperature only, being
dans un determined by the condition that, at
mélange constant temperature and
gazeux composition, p /p˜ tends to 1 for
B B
an indefinitely dilute gas
�
� �
9-21 standard chemical µ value of the chemical potential
B
µ = RT In λ
(—) potential of (item 9-17) at standard conditions
�
µ is a function of
substance B
B
temperature T at the standard
fr potentiel (m)
�
chimique de pressure .p = p
référence du
The standard chemical
constituant B
potential depends on the
choice of standard state, which
�
9-22.1 standard chemical µ for a pure phase, or a mixture, or a
shall be specified.
B
(—) potential of solvent, the chemical potential
The plimsoll sign is used to
substance B in a (item 9-17) of the pure substance B
denote a standard in general.
pure phase or a under standard pressure
The degree sign can also be
mixture or a
used for this. In a liquid or solid
solvent
solution, the standard state is
fr potentiel (m)
referenced to the ideal dilute
chimique de
behaviour of the solute
référence du
(substance B).
constituant B
dans une
phase pure,
un mélange ou
un solvant
�
9-22.2 standard chemical µ for a solute in solution, the
B
�
(—) potential of chemical potential, µ in the
B
substance B in (hypothetical) state of solute B at
�
a solution the standard molality, b (item
�
fr potentiel (m) 9-16), and standard pressure, p
chimique de (ISO 80000-4:2006, item 4-15.1),
référence du and behaving like an infinitely dilute
constituant B solution:
dans une
�
�
µ = lim µ − RT ln(y p/p )
solution B B
B
p→0
where y is amount-of-substance
B
fraction (item 9-14)
©
12 ISO 2009 – All rights reserved

ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-20.a pascal Pa
9-21.a joule per mole J/mol
9.22.a joule per mole J/mol
(continued)
©
ISO 2009 – All rights reserved 13

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
∗
9-23 activity factor of f f = λ /(λ x ) The systematic name is
B B B B
B
(8-22.1) substance B in a “activity factor”, but the name
where λ is the absolute activity of
B
liquid or a solid “activity coefficient” is also
∗
substance B (item 9-18), λ is the
B
mixture commonly used.
absolute activity of the pure
activity coefficient
substance B at the same
of substance B in
temperature and pressure, and x
B
a liquid or a solid
is the amount-of-substance fraction
mixture
of substance B (item 9-14)
fr facteur (m)
d'activité du
constituant B
dans un
mélange
liquide ou
solide
9-24.1 activity factor
f f = a /x
B B B B
(—) referenced to
where a is the activity of solute B
B
Raoult's law
x
(item 9-26) and is the amount-
B
fr facteur (m)
of-substance fraction of B (item
d'activité
9-14)
référencé à la
loi de Raoult
9-24.2 activity factor γ , γ , γ There are three different cases for
m c x
(—) referenced to the activity factor referenced to
Henry's law Henry's law: molality basis, γ ,
m
fr facteur (m) concentration basis, γ , and
c
d'activité amount-of-substance basis, γ :
x
référencé à la
a
m,B
loi de Henry
γ =
m,B �
b /b
B
a
c,B
γ =
c,B
�
c /c
B
a
x,B
γ =
x,B
x
B
�
� � ∗
9-25 standard absolute λ λ = λ (p ) This quantity is a function of
B B B
(8-22.2) activity of temperature only.
∗
where λ is the absolute activity
B
substance B in a
(item 9-18) of the pure substance B The standard pressure is
liquid or a solid
at the same temperature and 10 Pa.
mixture �
pressure, and p is standard
fr activité (f)
pressure (ISO 80000-4:2006, item
absolue
4-15.1)
normale du
constituant B
dans un
mélange
liquide ou
solide
©
14 ISO 2009 – All rights reserved

ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-23.a one 1 See the Introduction, 0.3.2.
9-24.a one 1 See the Introduction, 0.3.2.
9-25.a one 1 See the Introduction, 0.3.2.
(continued)
©
ISO 2009 – All rights reserved 15

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
�
9-26 activity of solute B, a , a for a solute B in a solution, a is
B m,B B
b /b
B
a = λ · lim
(8-23) relative activity of
proportional to the absolute activity, B B �
λ
b →0 B
B
solute B
λ (item 9-18), the proportionality
B
fr activité (f) du
factor, which is a function of The quantity a , similarly
c,B
soluté B,
temperature and pressure only, defined in terms of the
activité (f) relative
�
being determined by the condition concentration ratio c /c , is
B
du soluté B
that, at constant temperature and also called the activity or
pressure, a divided by the molality relative activity of solute B;
B
� �
ratio, b /b , tends to 1 at infinite c is a standard
B
dilution; b is the molality of solute concentration, usually
B
�
B (item 9-16), and b is standard 1 mol/dm :
molality, usually 1 mol/kg
�
c /c
B
a = λ · lim
c,B B �
λ
c →0 B
B
where Σ denotes summation
over all the solute substances.
This especially applies to a
dilute liquid solution.
9-27 activity coefficient γ for a solute in a solution, The name “activity coefficient
B
(8-24.1) of solute B of solute B” is also used for the
a
B
fr facteur (m) quantity γ defined as
γ =
B
B
�
b /b
d'activité du B
a
c,B
soluté B
γ =
B
where a is the activity of solute B �
B
c /c
B
(item 9-26), b is the molality of
B
�
See item 9-26.
substance B, and b is standard
molality
�
9-28 standard absolute λ for a solute B in a solution, This quantity is a function of
B
(8-24.2) activity of � � � � temperature only. It especially
� �
�
λ = lim λ p b /b
solute B B B applies to a dilute liquid
�
B
b →0
B
fr activité (f) solution. The standard
absolue pressure is 10 Pa.
Σ
where denotes summation over
�
normale du
all solutes, p is a standard
soluté B
pressure (ISO 80000-4:2006,
�
item 4-15.1), b is standard
molality, and b is the molality of
B
substance B (item 9-16)
©
16 ISO 2009 – All rights reserved

ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-26.a one 1 See the Introduction, 0.3.2.
9-27.a one 1 See the Introduction, 0.3.2.
9-28.a one 1 See the Introduction, 0.3.2.
(continued)
©
ISO 2009 – All rights reserved 17

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
∗
9-29.1 activity of solvent A, a for the solvent A in a solution, ratio a = λ /λ
A A A
A
(8-25.1) relative activity of of the absolute activity of
solvent A substance A, λ (item 9-18), to
A
∗
fr activité (f) du that, λ , of the pure solvent at the
A
solvant A, same temperature and pressure
activité (f) relative
du solvant A
�
−1
9-29.2 osmotic factor of ϕ ϕ =−(M b ) ln a The name “osmotic coefficient”
A B A
(8-25.2) solvent A, is generally used, although the
where M is the molar mass
A
osmotic coefficient name “osmotic factor” is more
(item 9-5) of the solvent A, Σ
of solvent A systematic. This especially
denotes summation over all the
fr facteur (m) applies to a dilute liquid
solutes, b is the molality of solute
B
osmotique du solution.
B (item 9-16), and a is the activity
A
solvant A
of solvent A (item 9-29.1)
�
9-29.3 standard absolute for the solvent A in a solution, the The standard pressure is
λ
A
(8-25.3) activity of absolute activity (item 9-18) of the 10 Pa.
solvent A pure substance A at the same
(especially in a temperature and at a standard
�
dilute liquid pressure p (ISO80000-4:2006,
solution) item 4-15.1):
fr activité (f)
�
�
∗
absolue λ = λ p
A A
normale du
solvant A
(particuliè-
rement en
solution liquide
diluée)
9-30 osmotic pressure Π excess pressure required to
(8-26) fr pression (f) maintain osmotic equilibrium
osmotique between a solution and the pure
solvent separated by a membrane
permeable to the solvent only
EXAMPLE
9-31 stoichiometric ν number or simple fraction occurring
B
(1/2)N + (3/2)H = NH
(8-27) number of in the expression for a chemical 2 2 3
ν(N ) =−1/2,
substance B reaction: 0 =Σν B, where the
B
ν(H ) =−3/2,
fr nombre (m) symbol B denotes the reactants
ν(NH )=+1.
stœchio- and products involved in the
métrique du reaction
The stoichiometric number is
constituant B
negative for a reactant and
positive for a product.
©
18 ISO 2009 – All rights reserved

ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-29.a one 1 See the Introduction, 0.3.2.
9-30.a pascal Pa
9-31.a one 1 See the Introduction, 0.3.2.
(continued)
©
ISO 2009 – All rights reserved 19

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
9-32 affinity of a A A =−Σν µ The affinity of a reaction is a
B B
(8-28) chemical reaction measure of the “driving force”
where ν is the stoichiometric
B
fr affinité (f) d'une of the reaction. When it is
number of substance B (item 9-31)
réaction positive, the reaction goes
and µ is the chemical potential of
B
chimique spontaneously from reactants
substance B (item 9-17)
to products, and when it is
negative, the reaction goes in
The summation goes over all
substances B. the opposite direction.
Another way to write the
definition is:
A =−(∂G/∂ξ)
p,T
where G is Gibbs energy
(ISO 80000-5:2007, item
5-20.5) and ξ is the extent of
the reaction (item 9-33).
Note that ν is negative for
B
reactants and positive for
products.
ξ dn =ν dξ
9-33 extent of reaction See remark to item 9-31.
B B
(8-29) fr état (m)
where n is the amount of
B
d'avancement
ν
substance B (item 9-1) and is
B
d'une réaction
the stoichiometric number of
substance B (item 9-31)
�
9-34 standard K for a chemical reaction, This quantity is a function of
(8-30) equilibrium � −ν temperature only.
�
B
K =Π (λ )
B
B
constant,
Others depend on
thermodynamic
where Π denotes the product for
B
temperature, pressure, and
�
equilibrium all substances B, λ is the
B
composition, as follows.
constant
standard absolute activity of
fr constante (f) substance B (item 9-25) and ν is One can define in an
B
d'équilibre
the stoichiometric number of analogous way an equilibrium
normale substance B (item 9-31) constant in terms of fugacity,
K , molality, K , etc.
f m
ν
B
9-35 equilibrium K K =Π (p ) for gases
p p B B
constant on a
pressure basis
fr constante (f)
d'équilibre
pour les
pressions
©
20 ISO 2009 – All rights reserved

ISO 80000-9:2009(E)
UNITS PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
Inter-
Conversion factors and
Item No. Name national Definition
remarks
symbol
9-32.a joule per mole J/mol
9-33.a mole mol
9-34.a one 1 See the Introduction, 0.3.2.
Σν
9-35.a pascal to the B
Pa
power sum of
stoichiometric
numbers
(continued)
©
ISO 2009 – All rights reserved 21

ISO 80000-9:2009(E)
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS QUANTITIES
Item No. Name Symbol Definition Remarks
ν
B
9-36 equilibrium K K =Π (c ) for solutions
c c B B
constant on a
concentration
basis
fr constante (f)
d'équilibre
pour les
concentrations
9-37 electric dipole p, (µ) E = –p · E The moment of force M acting
p
(8-32) moment of a in an electric field E on a
where E is the interaction
...