Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. इंटरनेट मानक “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda “Invent a New India Using Knowledge” “प0रा1 को छोड न’ 5 तरफ” Jawaharlal Nehru “Step Out From the Old to the New” “जान1 का अ+धकार, जी1 का अ+धकार” Mazdoor Kisan Shakti Sangathan “The Right to Information, The Right to Live” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 1890-8 (1995): Quantities and Units, Part 8: Physical chemistry and molecular physics [PGD 1: Basic Standards]
Transcript
Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.
इंटरनेट मानक
“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru
“Step Out From the Old to the New”
“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan
“The Right to Information, The Right to Live”
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
“Invent a New India Using Knowledge”
है”ह”ह
IS 1890-8 (1995): Quantities and Units, Part 8: Physicalchemistry and molecular physics [PGD 1: Basic Standards]
August 1995
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
/ndian Standard QUANTITIES AND UNITS
PART 8 PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
( First Revision )
UDC 53.081
0 BIS 1995
BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
Price Group 10
b
Basic Standards Sectional Committee, MSD 1
NATIONAL FOREWORD
This Indian Standard (Part 8) (First Revision) which is identical with IS0 31-8 : 1992, issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Basic Standards Sectional Committee (MSD 1) and approval of the Management and Systems Division Council.
The text of the IS0 Standard has been approved as suitable for publication as Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:
Comma (,) has been used as a decimal marker while in Indian Standards the current practice is to use a point (.) as the decimal marker.
Wherever the words ‘International Standard’ appear, referring to this standard, they should be read as ‘Indian Standard.
This standard was first published in 1983. In this revision, following changes have been made:
a) The decision by the International Committee for Weights and Measures (CIPM) in 1980 concerning the status of supplementary units has been incorporated;
b) A number of new quantities and their units have been added such as extent of reaction, angle of optical rotation, molar optical rotatory power and specific optical rotatory power; and
c) Six new chemical elements given atomic numbers 104 to 109 have been added in Annex A (Normative).
ADDITIONAL INFORMATION
IS 189O/ISO 31 consists of the following parts, under the general title ‘Quantities and Units’:
international Standard Corresponding Indian Degree of Standard Equivalence
IS0 31-O : 1992 IS 1890 (Part 0) : 1995 Quantities Identical and units : Part 0 General principles (first revision)
IS0 31-1 : 1992 IS 1890 (Part 1) : 1995 Quantities Identical and units : Part 1 Space and time (third revision)
IS0 31-2 : 1992 IS 1890 (Part 2) : 1995 Quantities Identical and units : Part 2 Periodic and re- lated phenomena (second revision)
IS0 31-3 : 1992 IS 1890 (Part 3) : 1995 Quantities Identical and units : Part 3 Mechanics (second revision)
IS0 31-4 : 1992 IS 1890 (Part 4) : 1982* Quantities, Technically units and symbols : Part 4 Heat (first Equivalent revision)
IS0 31-5 : 1992 IS 1890 (Part 5) : 1995 Quantities Identical and units : Part 5 Electricity and magnetism (first revision)
(Continued on third cove/j
IS 1890 (Part 8) : 1995 IS0 31-8: 1992
Indian Standard
QUANTITIES AND UNITS PART 8 PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
( First Revision)
1 scope
This part of IS0 31 gives names and symbols for quantities and units of physical chemistry and molecular physics. Where appropriate, conversion factors are also given.
2 Normative references
The following standards contain provisions which, through reference in’ this text, constitute provisions of this part of IS0 31. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of IS0 31 are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards.
IS0 3141992. Quantities and units - Part 4: Heat.
IS0 31-9:1992, Quantities and units - Part 9: Atomic and nuclear physics.
3 Names and symbols
The names and symbols for quantities and units of physical chemistry and molecular physics are given on the following pages.
IS 1890 (Part 8) : 1995 IS0 31-8: 1992
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS Quantities
Item No.
Quantity Symbol Definition Remarks
8-1.1 relative atomic A, Ratio of the average mass per EXAMPLE mass atom of an element to l/12 of A&I) = 35,453
the mass of an atom of the nuclide “C
Formerly called atoniic’tieight.
8-l .2 relative molecular M, Ratio of the average mass per Formerly called molecular mass molecule or specified entity of weight.
a substance to l/12 of the The relative atomic or molecu- ;ass of an atom of the nuclide lar mass depends on the
C nuclidic composition.
8-2 number of N Number of molecules or other molecules or other elementan/ entities in a system elementary entities
B-3 amount of n, (9 Amount of substance is one of substance the base quantities on which
the SI is based.
v may be used as an alternative to n when n is used for number density of particles (see 8-10.1).
8-4 Avogadro constant L, N, Number of molecules divided N, = (6,022 136 7 f by amount of substance. 0,000 003 6) x 10z3 mol-’ ‘)
NA = N/n
1) CODATA Bulletin 63 (1986).
8-5 molar mass M Mass divided by amount of m is the mass of the substance. substance.
M = m/n
8-6 molar volume “nl Volume divided by amount of The molar volume of an ideal substance. gas at 273,15 K and
101,325 kPa is V, = V/n V = (0,022 414 10 f
Or”d”oO 000 19) m3/mol ‘)
1) CODATA Bulletin 63 (1986).
2
c ” ‘-“p
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
Units
Item No.
Name of unit
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS
International symbol for Definition Conversion factors and remarks
unit
3-l .a one 1 See the introduction, subclause 0.3.2.
3-2.a one 1 See the introduction, subclause 0.3.2.
3-3.a mole mol The mole is the amount The definition applies to unbound at- of substance of a system oms of carbon 12, at rest and in their which contains as many ground state. elementary entities as there are atoms in 0,012 kilogram of carbon 12. When the mule is used, the elementary entities must be specified and may be atoms, mol- ecules, ions, electrons, other particles, or speci- fied groups of such par- ticles
8-4.a reciprocal mole,
mole to the power minus
one
mol-’
8-5 a kilogram per
mole
kg/mol M = 1 0e3 M, kg/mol = M, kg/km01 = Mr g/mol where Mr is the relative molecular mass of a substance of definite chemical composition.
8-6.a cubic metre per mole
m3/mol
3
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued) Quantities
item No.
Quantity Symbol Definition Remarks
B-7 molar url7 Thermodynamic energy divided This quantity is also called thermodynamic by amount of substance. molar internal energy. energy See IS0 31-4.
U, = U/n Similar definitions apply to other molar thermodynamic functions, for example
I=(,,, A,, G,
B-8 molar heat capacity C, Heat capacity divided by See IS0 31-4. amount of substance.
C, = C/n
R-9 molar entropy %l Entropy divided by amount of See IS0 31-4. substance.
S, = S/n
3-10.1 volumic number of n Number of molecules or par- molecules (or titles divided by volume. particles),
number density of n = NIV
molecules (or particles)
9-I 0.2 molecular Ca Number of molecules of B div- concentration of B ided by the volume of the mix-
ture
8-l 1 .I volumic mass, e Mass divided by volume mass density, density
8-l 1.2 mass concentration eB Mass of B divided by the voi-
of B ume of the mixture
8-12 mass fraction of B wB Ratio of the mass of B to the mass of the mixture
8-13 concentration of B, ca Amount of substance of B div- In chemistry also indicated as
amount-of-substance ided by the volume of the rnix- CBI. concentration of B ture
4
IS 1890 (Part 8) : 1995 IS0 31-8: 199i
Units PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continuea
Item International
No. Name of unit symbol for Deflnitlon Conversion factors and remarks
unit
8-7.a joule per mole J/mot For the various types of calorie, see IS0 3141992, annex 8.
B-8.a joule per mole kelvin
J/(mol - K)
3-9.a joule per mole kelvin
J/(mol a K)
3-l 0.a reciprocal cubic rnM3 metre,
metre to the power minus three
3-l 1 .a kilogram per kg/m3 cubic metre
_------L---------- B-l 1 .b kilogram per litre kg/l, kg/L
512.a one 1
B-13.a mole per cubic mol/m3 metre
---_-------_-- ----- ------ B-13.b mole per litre mol/l,
mol/L
1 kg/l = lo3 kg/m3 = 1 kg/dm3
The symbol L was adopted by the CGPM (1979) as an alternative to I for the litre.
See the introduction, subclause 0.3.2.
1 mol/l = IO3 mot/m3 = 1 mol/dm3
5
IS 1890 (Part.8) : 1995
IS0 31-8 : 1992
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued)
Item No.
Quantity Symbol Definition
Quantities
Remarks
$14.1 mole fraction of B xBl bd Ratio of the amount of sub- Alternative names for these I&3- 15.1) stance of B to the amount of quantities are “amount-of-
substance of the mixture substance fraction” and “amount-of-substance ratio”
3-l 4.2 mole ratio of solute ‘s Ratio of the amount of sub- respectively.
IS-lS.ZI B stance of B to the amount of For a one-solute solution,
substance of the solvent sub- r=x/(l -x)
stance
3-15 volume fraction of pB For a mixture of substances, An alternative definition in D-74.7) B
PB = xBv:,B
which the molar volumes VzA
WC,A of the pure substances A are replaced by the partial molar
where the V&, are the molar volumes of the pure sub- stances A at the same tem- perature and pressure and
volumes (~3V/iln,),,,,,,, of the substances A is also used.
where C denotes summation over all the substances
3-16 molality of solute B ba, ma Amount of substance of solute B in a solution divided by the mass of the solvent
3-17 chemical potential pa of B
For a mixture of substances B, For a pure substance, c, . . . . p = G/n = G
PB = (aG/anBb,,,,,...
where G, ismthe molar Gibbs function.
B-18
8-19
where ng iS the amOUnt of sub- The symbol p is also used for
stance of B and G is the Gibbs the quantity G,/N,, where NA is
function the Avogadro constant.
absolute activity of Ia 1, = exP(&/RT) For R, see 8-36. T is the B thermodynamic temperature.
partial pressure of Pa For a gaseous mixture, B (in a gaseous mixture) pa =xB’P
wherep is the pressure
8-20 fugacity of B (in a %I CfB) For a gaseous mixture, & is gaseous mixture) proportional to the absolute ac-
iB = 1-B ’ $~o(xep/nB)
tivity As, the proportionality fac- tor,,which is a function of temperature only, being deter- mined by the condition that at constant temperature and con?- position &/JIB tends to 1 for an infinitely dilute gas
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
Units PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued)
Item international
No. Name of unit symbol for Definition Conversion factors and remarks
unit
8-14.a one 1 See the introduction, subclause 0.3.2.
8-15.a one 1 See the introduction, subclause 0.3.2.
8-l 6.a mole per mol/kg kilogram
8-l 7.a joule per mole J/mol
8-18:a one
8-l 9.a Pascal
1
Pa
See the introduction, scbclause 0.3.2.
8-20.a Pascal Pa
IS 1890 (Part 8) : 1995 IS0 31-8: 1992
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued) Quantities
Item No.
Quantity Symbol Definition Remarks
8-21 standard absolute G 1; = (ha) - ;$pe/P) This quantity is a function of activity of B (in a gaseous mixture) where pe is a standard press-
temperature only.
ure, usually 101,325 kPa
3-22.1 activity coefficient fa For a liquid mixture, The name “activity factor” of B (in a liquid or would be more systematic. a solid mixture) fs = &J/G%)
where Ai is the absolute activity of the pure substance B at the same temperature and press- ure
3-22.2 standard absolute AL7 n; = A@“) This quantity is a function of activity of B (in a temperature only. liquid or a solid mixture)
j-23 activity of solute B, aB, %,B For a solute B in a solution, aa relative activity of is proportional to the absolute aB=lB. fim mslme
solute B activity ia, the proportionality Em,-+0 LB
(especially in a factor, which is a function of The quantity a,,, similarly de-
dilute liquid temperature and pressure only, fined in terms of the concen-
solution) being determined by the con- tration ratio ca/ce is also called
dition that at constant tempera- the activity or relative activity
ture and pressure aa divided by Of “lute B; ce is a Sandard the molality ratio ma/m* tends concentration, usually
to 1 at infinite dilution; ma is a 1 mol/dm3.
standard molality, usually 1 mol/kg U c,B =
1,. lim cslce XC,+0 ;L,
where C denotes summation over all the solute substances. The subscript c in a,,a iS often omitted.
IS 1890 (Part 8) : 1995 IS0 31-8: 1992
Units PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued)
Item International
No. Name of unit symbol for Definition Conversion factors and remarks
unit
3-21 .a one 1 See the introduction, subclause 0.3.2.
8-22.a one 1 See the introduction, subclause 0.3.2.
8-23 .a one 1 See the introduction, subclause 0.3.2.
9
IS 1890(Part8):1995 IS0 31-8:1992
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued)
Item No.
Quantity Symbol Definition
Quantities
Remarks
B-24.1 activity coefficient ya For a solute in a solution, The name activity coefficient of of solute B solute B is also used for the (especially in a yB =ag
mB/m’
quantity ys defined as dilute liquid solution)
% s yB = _-L___
ce/ce
See item 8-23.
The name “activity factor” would be more systematic.
3-24.2 standard absolute 1: For a solute B in a solution, This quantity is a function of activity of solute B (especially in a dilute liquid
$? =z$n_ o [AB(pe)me/mBl
temperature only.
solution) where c denotes summation over all solutes
3-25.1 activity of solvent a, For the solvent A in a solution, a, = .I,/,$
A, aA is equal to the ratio of the relative activity of absolute activity AA to that, Ai, solvent A of the pure solvent at the same (especially in a temperature and pressure dilute liquid solution)
3-25.2 osmotic coefficient rp of solvent A (especially in a dilute liquid solution)
p = - (&Ems) -’ ln aA The name “osmotic factor” would be more systematic.
where MA is the molar mass of the solvent A and where C de- notes summation over all the solutes
3-25.3 standard absolute 4? For the solvent A in a solution, This quantity is a function of activity of solvent temperature only. A (especially in a LA” = Li($)
dilute liquid solution)
8-26 osmotic pressure Excess pressure required to maintain osmotic equilibrium between a solution and the pure solvent separated by a membrane permeable only to the solvent
B-27 stoichiometric number of B
VB Numbers or simple fractions By convention, the occurring in the expression for stoichiometric numbers for a chemical reaction: 0 = CvgB, reactants are negative and where the symbol .B indicates those for products are positive. the molecules, atoms or ions involved in the reaction
IS 1890 (Part 8) : 1998 IS0 31-8: 1992
3
e
I
hits PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued)
Item International
No. Name of unit symbol for Definition Conversion factors and remarks
unit
-24.a one 1 See the introduction, subclause 0.3.2.
k25.a one 1 See the introduction, subclause 0.3.2.
3-26.a Pascal Pa
3-27.a one 1 See the introduction, subclause 0.3.2.
11
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
>HYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued) Quantities
Item No.
Quantity Symbol Definition Remarks
3-28 affinity (of a A A = - cv&.@ If A is used as symbol for
chemical reaction) Helmholtz free energy, an italic bold-face A, sans serif A or script A is often used as sym- bol for affinity.
3-29 1-1
extent of reaction C dna = vB dC
where aa is the amount of sub- stance of B
B-30 standard equilibrium Ke For a chemical reaction, Ke is This quantity is a function of
[&29.7) constant the product na (‘2:) -ys temperature only. Other “equilibrium constants” depend on temperature and pressure. EXAMPLES Kf = &(fe)‘” for gases, Kti = ~J,(z&)~~ for mixtures and K, = ~B(ag)YB for solutions.
Others depend on temperature, pressure and composition. EXAMPLES Kp = l’&(pB)“” for gases, K, = &(_Q)‘” for mixtures and
K,, = na(~)“~ or Kc = j&(+JyB for solutions.
Some of them (Kfi Kp, K,,,, Kc) are not always of dimension one (dimensionless). Similarly, the standard “solubility product” of a solution saturated by an electrolyte CAY is the quantity of dimension one Ke = xxyY(my/me)‘+Y where m is the molality and y the activity coefficient of CA, in the solution, and rn? is a standard molality, usually 1 mol/kg.
B-31 mass of molecule m m=M,m, (8-30.7) where m,, is the (unified) atomic
mass constant.
For m, see IS0 31-9.
12
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
Units PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continueb)
Item International
No. Name of unit symbol for Definition Conversion factors and remarks
unit
3-28.a joule per mole J/mol
?-29.a mole mol
3-30.a one 1 See the introduction, subclause 0.3.2.
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (conhued)
Item No.
Quantity Symbol Definition
Quantities
Remarks
3-32 electric dipole Pt P Vector quantity, the vector [&31.7) moment of product of which with the elec-
molecule tric field strength is equal to the torque.
pxE=T
3-33 electric polarizability CY Induced electric dipole moment y is also used. D-32.1) of molecule divided by electric field strength
8-34.1 microcanonical n n = Zrl S=kInn (8-33.7) partition function
where the sum is over all where S is the entropy.
quantum states consistent with given energy, volume, external fields and content
3-34.2 canonical partition k-33.2) function
Q, 2 Z = C, exp (-E,/kT) For k see 8-37. A=-kTInZ
where the sum is over all where A is the Helmholtz free quantum states consistent with given volume, ekternal fields
energy.
and content, and where E, is the energy of the rth quantum state
B-34.3 grand-canonical E z = A - CpsnB = - kT In E (8-33.3) partition function,
grand partition c ( Z NA, Ns, “‘) . ‘~. ‘~ ’ .” where 1s is the chemical po- tential of B.
function NA, NB,
where Z(N,, Na, . ..) is the canonical partition function for given numbers of particles A, B , . . . . and LA, I,, . . . . are the absolute activities of particles , A, B, . . .
8-34.4 molecular’partition q q = Ci exp (-&i/kT) (8-33.4) function,
partition function of where &i is the energy of the
a molecule ith’allowed quantum state of the molecule consrstent with given volume and external fields
8-35 statistical weight g Multiplicity (degeneracy) of (S34.1) quantum energy level
14
is 1890 (Part 8) : 1995 ISO 31-8 : 1992
Jnits
Item No.
Name of unit
M2.a coulomb metre
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (cohntied)
International symbol for Dafinition Conversion factors and remarks
unit
C - m The Gaussian CGS unit of electric dipole moment of a molecule corresponds to 3,335641 x 10-‘2C-m
I-33.a coulomb metre C - m2/V The Gaussian CGS unit of polarizability
squared per volt of a molecule equal to 1 cm3 corre- sponds to 1,112 650 x 10-‘6C.m2/V
C34.a one 1 See the introduction, subclause
0.3.2.
8-35.a one 1 See the introduction, subclause
013.2.
15
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
PHYSICAL CHEMISTRY AND MOLECULAR PHYSICS (continued)
Item No.
Quantity Symbol Definition
Quantities
Remarks
8-36 molar gas constant R The universal constant of pro- R = 8,314 510 f 0,000 070 E-35.1) portionality in the ideal gas law: J/(mol - K) ‘)
pV,,, = RT
1) CODATA Bulletin 63 (1986).
8-37 Boltzmann constant k k = R/N, k =’ 1 380 658 f 0,000 012) x (8-36. I) IO- IsI J/K ‘)
/I is used for l/kT, where T is the thermodynamic tempera- ture.
1) CODATA Bulletin 63 (1986).
8-38 mean free path I, 1 For a molecule, the average (8-37.1) distance between two suc-
cessive collisions
8-39 diffusion coefficient D G3 w = -D grad C, (8-38.7)
where Ca is the local molecular concentration of B in the mix- ture and (~a) is the local aver- age velocity of the molecules of B
8-40.1 thermal diffusion I+ In the steady state of a binary (8-39.7) ratio mixture in which thermal dif-
fusion occurs
grad X, = - (MT) grad T
where x6 is the local mole frac- tion of the heavier substance B and T is the local temperature
8-40.2 thermal diffusion ar (8-39.2) factor
where XA and xa are the local mole fractions of the two sub- stances
1) Quoted from: IUPAC, Physical Chemistry Division: Quantities, Units and Symbols in Physical Chemistry (1988). The names in parentheses are added for information.
22
IS 1890 (Part 8) : 1995 1SO 31-8: 1992
Atomic number Name Symbol
a7 francium Fr 88 radium Ra 89 actinium AC 96 thorium Th 91 protactinium Pa 92 uranium U
93 neptunium NP 94 plutonium Pu 95 americium Am 96 curium Cm 97 berkelium 9k 98 californium Cf 99 einsteinium Es
100 fermium Fm 101 mendelevium Md 102 nobelium No 103 lawrencium Lr
104 unnilquadium Unq 105 unnilpentium Unp 106 unnilhexium Unh 107 unnilseptium Uns 108 unniloctium Uno 109 unnilennium Une
23
IS 1890 (Part 8) : 1995 IS0 31-8: 1992
Annex B (normative)
Symbols for chemical elements and nuclides
Symbols for chemical elements shall be written in roman (upright) type. The symbol is not followed by a full stop.
EXAMPLES
H He C Ca
The attached subscripts or superscripts specifying a nuclide or molecule shall have the following meanings and positions.
The nucleon number (mass number) of a nuclide is shown in the left superscript position, for example
14 N
The number of atoms of a nuclide in a molecule is shown in the right subscript position, for example
14N 2
The proton number (atomic number) may be indicated in the left subscript position, for example
64Gd
If necessary, a state of ionization or an excited state may be indicated in the right superscript position.
EXAMPLES
State of ionization: Na+, PO:- or (P04j3-
Electric excited state: He*, NO’
Nuclear excited state: ttOAg* or lloAgm
24
IS 1890 (Part 8) : 1995 IS0 31-8 : 1992
Annex C (normative)
pH is defined operationally. For a solution X, the electromotive force Ex of the galvanic cell:
reference electrode 1 concentrated solution of KCI ( solution X 1 H, ( Pt
is measured, and likewise the electromotive force Es of a galvanic cell that differs only by the replacement of the solution X of unknown pH, pH(X), by a solution S of standard pH, pH(S). Then
pH(X) = pH(S) -+ (Es - &JF/(RT In
where
F is the Faraday constant;
R is the molar gas constant;
‘0)
T is the thermodynamic temperature.
Thus defined, pH is a quantity of dimension one.
Values of pH(S) for standard solutions are listed in “Definitions of .pH Scales, Standard Reference Values, Measurement of pH, and Related Terminology” Pure Appl. Bern. (19851, 57, pp. 531-542, where further details can be found.
pH has no fundamental meaning; the definition is a practical one. However, in the restricted range of di- lute aqueous solutions having amount-of-substance concentrations less than 0,l mol/dm3 and being nei- ther strongly acidic nor strongly alkaline (2 < pH < 12), the definition is such that
pH = - Ig[c(H+)y,/(mol - dmW3)] f 0,02
where c(H+) denotes the amount-of-substance con- centration of hydrogen ion H+ and y, denotes the ac- tivity coefficient of a typical uni-univalent electrolyte in the solution.
25
(Continued from second cover)
In terna tional Standard
IS0 31-6 : 1992
IS0 31-7 : 1992
IS0 31-8 : 1992
IS0 31-9 : 1992
IS0 31-10 : 1992
ISO31-11 : 1992
IS0 31-12 : 1992
IS0 31-13 : 1992
Corresponding Indian Degree of Standard Equivalence
IS 1890 (Part 6) : 1983*Quantities, units and symbols : Part 6 Light and related electromagnetic radiations
Technically Equivalent
IS 1890 (Part 7) : 1995 Quantities and units: Part 7 Acoustics (first revision)
Identical
IS 1890 (Part 8) : 1995 Quantities and units : Part 8 Physical chemistry and molecular physics (first revision)
Identical
IS 1890 (Part 9) : 1995 Quantities and units : Part 9 Atomic and nuclear physics (first revision)
Identical
IS 1890 (Part 10) : 1995 Quantities and units : Part 10 Nuclear reactions and ionizing radiation (first revision)
IS 1890 (Part 11) : 1995 Quantities and units : Part 11 Mathematical signs and symbols for use in the physical science and technology (second revision)
IS 1890 (Part 12) : 1995 Quantities and units : Part 12 Characteristic numbers (first revision)
IS 1890 (Part 13) : 1983* Quantities, units and symbols : Part 13 Solid state physics
Identical
Identical
Identical
Technically Equivalent
* Under revision
Bureau of Indian Standards
BIS is a statutory institution established under the Bureau of Indim Standards Act, I986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country.
Copyright
BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publications), BIS.
Review of India’n Standards
Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards Monthly Additions’.
This Indian Standard has been developed from Doe : IQ), MSD 01 (91)
Amendments Issued Since Publication
Amend No. Date of Issue Text Affected
BUREAU OF INDIAN STANDARDS
Headquarters:
Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 1 loo02 Telegrams : Manaksanstha Telephones : 3310131,331 13 75 (Common to all offices)
Regional Offices’: Telephone
Central : Manak Bhavan, 9 Bahadur Shah Zafar Marg 3310131 NEW DELHI 1 loo02 33113 75
Eastern : l/14 C. I.T, Scheme VII M, V. I. P. Road, Mimiktola 37 84 99,37 85 61 CALCUTTA 7OOQ.54 378626,378662
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