Defining equation ( physical chemistry ) - wikipedia Defining equation ( physical chemistry ) For the detailed nature of defining equations, see Physical quantity. For a summary of thermodynamic quantities, see defining equation ( physics ). Main article : Physical chemistry In physical chemistry, there are numerous quantities associated with chemical compounds and reactions ; notably in terms of amounts of substance, activity or concentration of a substance, and the rate of reaction. This article uses SI units. Contents 1 Introduction 2 Notes on nomenclature 3 Quantification 3.1 General basic quantities 3.2 General derived quantities 4 Kinetics and equilibria 5 Electrochemistry 6 Quantum chemistry 7 References 8 Sources 9 Further reading Introduction Theoretical chemistry requires quantities from core physics, such as time, volume, temperature, and pressure. But the highly quantitative nature of physical chemistry, in a more specialized way than core physics, uses molar amounts of substance rather than simply counting numbers ; this leads to the specialized definitions in this article. Core physics itself rarely uses the mole, except in areas overlapping thermodynamics and chemistry. Notes on nomenclature Entity refers to the type of particle / s in question, such as atoms, molecules, complexes, radicals, ions, electrons etc. Conventionally for concentrations and activities, square brackets ( ) are used around the chemical molecular formula. For an arbitrary atom, generic letters in upright non-bold typeface such as A, B, R, X or Y etc. are often used. No standard symbols are used for the following quantities, as specifically applied to a substance : the mass of a substance m, the number of moles of the substance n, partial pressure of a gas in a gaseous mixture p ( or P ), some form of energy of a substance ( for chemistry enthalpy H is common ), entropy of a substance S the electronegativity of an atom or chemical bond χ. Usually the symbol for the quantity with a subscript of some reference to the quantity is used, or the quantity is written with the reference to the chemical in round brackets. For example, the mass of water might be written in subscripts as m, m, m, m ( if clear from context ) etc., or simply as m ( H O ). Another example could be the electronegativity of the fluorine - fluorine covalent bond, which might be written with subscripts χ, χ or χ etc., or brackets χ ( F-F ), χ ( FF ) etc. Neither is standard. For the purpose of this article, the nomenclature is as follows, closely ( but not exactly ) matching standard use. For general equations with no specific reference to an entity, quantities are written as their symbols with an index to label the component of the mixture - i.e. q. The labeling is arbitrary in initial choice, but once chosen fixed for the calculation. If any reference to an actual entity ( say hydrogen ions H ) or any entity at all ( say X ) is made, the quantity symbol q is followed by curved ( ) brackets enclosing the molecular formula of X, i.e. q ( X ), or for a component i of a mixture q ( X ). No confusion should arise with the notation for a mathematical function. Quantification General basic quantities Quantity ( Common Name / s ) ( Common ) Symbol / s SI Units Dimension Number of molecules dimensionless dimensionless Mass m kg ( M ) Number of moles, amount of substance, amount n mol ( N ) Volume of mixture or solvent, unless otherwise stated V m ( L ) General derived quantities Main article : Concentration Quantity ( Common Name / s ) ( Common ) Symbol / s Defining Equation SI Units Dimension Relative atomic mass of an element A, A, m A r ( X ) = ⟨ m ( X ) ⟩ m ( 12 C ) / 12 ( displaystyle A_ ( r ) left ( ( \rm ( X ) ) \right ) = ( \frac ( langle m left ( ( \rm ( X ) ) \right ) \rangle ) ( m left ( ^ ( 12 ) ( \rm ( C ) ) \right ) / 12 ) ) ) The average mass ⟨ m ( X ) ⟩ ( displaystyle langle m left ( ( \rm ( X ) ) \right ) \rangle ) is the average of the T masses m ( X ) corresponding the T isotopes of X ( i is a dummy index labelling each isotope ) : ⟨ m ( X ) ⟩ = 1 T ∑ i T m ( X i ) ( displaystyle langle m left ( ( \rm ( X ) ) \right ) \rangle = ( \frac ( 1 ) ( T ) ) sum _ ( i ) ^ ( T ) m left ( ( \rm ( X ) ) _ ( i ) \right ) ) dimensionless dimensionless Relative formula mass of a compound, containing elements X M, M, m M r ( Y ) = ∑ j N ( X j ) A r ( X j ) = ∑ j N ( X j ) ⟨ m ( X j ) ⟩ m ( 12 C ) / 12 ( displaystyle M_ ( r ) left ( ( \rm ( Y ) ) \right ) = sum _ ( j ) N left ( ( \rm ( X ) ) _ ( j ) \right ) A_ ( r ) left ( ( \rm ( X ) ) _ ( j ) \right ) = ( \frac ( sum _ ( j ) N left ( ( \rm ( X ) ) _ ( j ) \right ) langle m left ( ( \rm ( X ) ) _ ( j ) \right ) \rangle ) ( m left ( ^ ( 12 ) ( \rm ( C ) ) \right ) / 12 ) ) ) j = index labelling each element, N = number of atoms of each element X. dimensionless dimensionless Molar concentration, concentration, molarity of a component i in a mixture c, ( X ) c i = ( X i ) = d n i d V ( displaystyle c_ ( i ) = left ( ( \rm ( X ) ) _ ( i ) \right ) = ( \frac ( mathrm ( d ) n_ ( i ) ) ( mathrm ( d ) V ) ) ) mol dm = 10 mol m ( N ) ( L ) Molality of a component i in a mixture b, b ( X ) b i = n i m s o l v ( displaystyle b_ ( i ) = ( \frac ( n_ ( i ) ) ( m_ ( \rm ( solv ) ) ) ) ) where solv = solvent ( liquid solution ). mol kg ( N ) ( M ) Mole fraction of a component i in a mixture x, x ( X ) x i = n i n m i x ( displaystyle x_ ( i ) = ( \frac ( n_ ( i ) ) ( n_ ( \rm ( mix ) ) ) ) ) where Mix = mixture. dimensionless dimensionless Partial pressure of a gaseous component i in a gas mixture p, p ( X ) p ( X i ) = x i p ( m i x ) ( displaystyle p left ( ( \rm ( X ) ) _ ( i ) \right ) = x_ ( i ) p left ( ( \rm ( mix ) ) \right ) ) where mix = gaseous mixture. Pa = N m ( M ) ( T ) ( L ) Density, mass concentration ρ, γ, ρ ( X ) ρ = m i / V ( displaystyle \rho = m_ ( i ) / V , ! ) kg m ( M ) ( L ) Number density, number concentration C, C ( X ) C i = N i / V ( displaystyle C_ ( i ) = N_ ( i ) / V , ! ) m ( L ) Volume fraction, volume concentration φ, φ ( X ) φ i = V i V m i x ( displaystyle phi _ ( i ) = ( \frac ( V_ ( i ) ) ( V_ ( \rm ( mix ) ) ) ) ) dimensionless dimensionless Mixing ratio, mole ratio r, r ( X ) r i = n i n m i x − n i ( displaystyle r_ ( i ) = ( \frac ( n_ ( i ) ) ( n_ ( \rm ( mix ) ) - n_ ( i ) ) ) ) dimensionless dimensionless Mass fraction w, w ( X ) w i = m i / m m i x ( displaystyle w_ ( i ) = m_ ( i ) / m_ ( \rm ( mix ) ) , ! ) m ( X ) = mass of X dimensionless dimensionless Mixing ratio, mass ratio ζ, ζ ( X ) ζ i = m i m m i x − m i ( displaystyle zeta _ ( i ) = ( \frac ( m_ ( i ) ) ( m_ ( \rm ( mix ) ) - m_ ( i ) ) ) ) m ( X ) = mass of X dimensionless dimensionless Kinetics and equilibria The defining formulae for the equilibrium constants K ( all reactions ) and K ( gaseous reactions ) apply to the general chemical reaction : ν 1 X 1 + ν 2 X 2 + ⋯ + ν r X r ↽ − − ⇀ η 1 Y 1 + η 2 Y 2 + ⋯ + η p Y p ( displaystyle ( ce ( ( \nu _ ( 1 ) X1 ) + ( \nu _ ( 2 ) X2 ) + cdots + \nu _ ( mathit ( r ) ) X_ ( mathit ( r ) ) < = > ( eta _ ( 1 ) Y1 ) + ( eta _ ( 2 ) Y2 ) + cdots + eta _ ( mathit ( p ) ) ( Y ) _ ( mathit ( p ) ) ) ) ) and the defining equation for the rate constant k applies to the simpler synthesis reaction ( one product only ) : ν 1 X 1 + ν 2 X 2 + ⋯ + ν r X r ⟶ η Y ( displaystyle ( ce ( ( \nu _ ( 1 ) X1 ) + ( \nu _ ( 2 ) X2 ) + cdots + \nu _ ( mathit ( r ) ) X_ ( mathit ( r ) ) - > eta ( Y ) ) ) ) where : i = dummy index labelling component i of reactant mixture, j = dummy index labelling component i of product mixture, X = component i of the reactant mixture, Y = reactant component j of the product mixture, r ( as an index ) = number of reactant components, p ( as an index ) = number of product components, ν = stoichiometry number for component i in product mixture, η = stoichiometry number for component j in product mixture, σ = order of reaction for component i in reactant mixture. The dummy indices on the substances X and Y label the components ( arbitrary but fixed for calculation ) ; they are not the numbers of each component molecules as in usual chemistry notation. The units for the chemical constants are unusual since they can vary depending on the stoichiometry of the reaction, and the number of reactant and product components. The general units for equilibrium constants can be determined by usual methods of dimensional analysis. For the generality of the kinetics and equilibria units below, let the indices for the units be ; S 1 = ∑ j = 1 p η j − ∑ i = 1 r ν i, S 2 = 1 − ∑ i = 1 r σ i. ( displaystyle S_ ( 1 ) = sum _ ( j = 1 ) ^ ( p ) eta _ ( j ) - sum _ ( i = 1 ) ^ ( r ) \nu _ ( i ) ,, quad , S_ ( 2 ) = 1 - sum _ ( i = 1 ) ^ ( r ) sigma _ ( i ) ,. ) Click here to see their derivation For the constant K ; Substitute the concentration units into the equation and simplify :, K c = ∏ j = 1 p ( Y j ) y j ∏ i = 1 r ( X i ) x i ( K c ) = ∏ j = 1 p ( M ) y j ∏ i = 1 r ( M ) x i = ( M ) y 1 ( M ) y 2 ⋯ ( M ) y p ( M ) x 1 ( M ) x 2 ⋯ ( M ) x r = ( M ) ∑ j = 1 p y j ( M ) ∑ i = 1 r x i = ( M ) ∑ j = 1 p y j − ∑ i = 1 r x i ( M = mol dm − 3 ) ( displaystyle ( \begin ( aligned ) K_ ( c ) & = ( \frac ( prod _ ( j = 1 ) ^ ( p ) left ( ( ce ( Y ) ) _ ( j ) \right ) ^ ( y_ ( j ) ) ) ( prod _ ( i = 1 ) ^ ( r ) left ( ( ce ( X ) ) _ ( i ) \right ) ^ ( x_ ( i ) ) ) ) left ( K_ ( c ) \right ) & = ( \frac ( prod _ ( j = 1 ) ^ ( p ) ( ( ce ( M ) ) ) ^ ( y_ ( j ) ) ) ( prod _ ( i = 1 ) ^ ( r ) ( ( ce ( M ) ) ) ^ ( x_ ( i ) ) ) ) & = ( \frac ( ( ( ce ( M ) ) ) ^ ( y_ ( 1 ) ) ( ( ce ( M ) ) ) ^ ( y_ ( 2 ) ) cdots ( ( ce ( M ) ) ) ^ ( y_ ( p ) ) ) ( ( ( ce ( M ) ) ) ^ ( x_ ( 1 ) ) ( ( ce ( M ) ) ) ^ ( x_ ( 2 ) ) cdots ( ( ce ( M ) ) ) ^ ( x_ ( r ) ) ) ) & = ( \frac ( ( ( ce ( M ) ) ) ^ ( sum _ ( j = 1 ) ^ ( p ) y_ ( j ) ) ) ( ( ( ce ( M ) ) ) ^ ( sum _ ( i = 1 ) ^ ( r ) x_ ( i ) ) ) ) & = ( ( ce ( M ) ) ) ^ ( sum _ ( j = 1 ) ^ ( p ) y_ ( j ) - sum _ ( i = 1 ) ^ ( r ) x_ ( i ) ) end ( aligned ) ) ( ( ce ( M = mol ; dm ^ ( - 3 ) ) ) ) ) The procedure is exactly identical for K. For the constant k k = d ( Y ) d t ∏ i = 1 r ( X i ) σ i ( k ) = ( M ) s − 1 ∏ i = 1 r ( M ) σ i = ( M ) s − 1 ( M ) ∑ i = 1 r σ i = ( M ) 1 − ∑ i = 1 r σ i s − 1 ( displaystyle ( \begin ( aligned ) k& = ( \frac ( \frac ( mathrm ( d ) ( ( ce ( Y ) ) ) ) ( mathrm ( d ) t ) ) ( prod _ ( i = 1 ) ^ ( r ) left ( ( ce ( X ) ) _ ( i ) \right ) ^ ( sigma _ ( i ) ) ) ) left ( k \right ) & = ( \frac ( ( ( ce ( M ) ) ) s ^ ( - 1 ) ) ( prod _ ( i = 1 ) ^ ( r ) ( ( ce ( M ) ) ) ^ ( sigma _ ( i ) ) ) ) & = ( \frac ( ( ( ce ( M ) ) ) s ^ ( - 1 ) ) ( ( ( ce ( M ) ) ) ^ ( sum _ ( i = 1 ) ^ ( r ) sigma _ ( i ) ) ) ) & = ( ( ce ( M ) ) ) ^ ( 1 - sum _ ( i = 1 ) ^ ( r ) sigma _ ( i ) ) s ^ ( - 1 ) end ( aligned ) ) ) Quantity ( Common Name / s ) ( Common ) Symbol / s Defining Equation SI Units Dimension Reaction progress variable, extent of reaction ξ ξ ( displaystyle \xi ) dimensionless dimensionless Stoichiometric coefficient of a component i in a mixture, in reaction j ( many reactions could occur at once ) ν ν i j = d N i d ξ j ( displaystyle \nu _ ( ij ) = ( \frac ( mathrm ( d ) N_ ( i ) ) ( mathrm ( d ) \xi _ ( j ) ) ) , ) where N = number of molecules of component i. dimensionless dimensionless Chemical affinity A = − ( ∂ G ∂ ξ ) P, T ( displaystyle A = - left ( ( \frac ( partial G ) ( partial \xi ) ) \right ) _ ( P, T ) ) J ( M ) ( L ) ( T ) Reaction rate with respect to component i r, R R i = 1 ν i d ( X i ) d t ( displaystyle R_ ( i ) = ( \frac ( 1 ) ( \nu _ ( i ) ) ) ( \frac ( mathrm ( d ) left ( mathrm ( X ) _ ( i ) \right ) ) ( mathrm ( d ) t ) ) ) mol dm s = 10 mol m s ( N ) ( L ) ( T ) Activity of a component i in a mixture a i = e ( μ i − μ i ⊖ ) / R T ( displaystyle a_ ( i ) = e ^ ( left ( mu _ ( i ) - mu _ ( i ) ^ ( ominus ) \right ) / RT ) ) dimensionless dimensionless Mole fraction, molality, and molar concentration activity coefficients γ for mole fraction, γ for molality, γ for molar concentration. Three coefficients are used ; a i = γ x i x i ( displaystyle a_ ( i ) = gamma _ ( xi ) x_ ( i ) , ) a i = γ b i b i / b ⊖ ( displaystyle a_ ( i ) = gamma _ ( bi ) b_ ( i ) / b ^ ( ominus ) , ) a i = γ c i ( X i ) / ( X i ) ⊖ ( displaystyle a_ ( i ) = gamma _ ( ci ) left ( mathrm ( X ) _ ( i ) \right ) / left ( mathrm ( X ) _ ( i ) \right ) ^ ( ominus ) , ) dimensionless dimensionless Rate constant k k = d ( Y ) / d t ∏ i = 1 r ( X i ) σ i ( displaystyle k = ( \frac ( mathrm ( d ) left ( mathrm ( Y ) \right ) / mathrm ( d ) t ) ( prod _ ( i = 1 ) ^ ( r ) left ( mathrm ( X ) _ ( i ) \right ) ^ ( sigma _ ( i ) ) ) ) ) ( mol dm ) s ( ( N ) ( L ) ) ( T ) General equilibrium constant K c = ∏ j = 1 p ( Y j ) η j ∏ i = 1 r ( X i ) ν i ( displaystyle K_ ( c ) = ( \frac ( prod _ ( j = 1 ) ^ ( p ) left ( mathrm ( Y ) _ ( j ) \right ) ^ ( eta _ ( j ) ) ) ( prod _ ( i = 1 ) ^ ( r ) left ( mathrm ( X ) _ ( i ) \right ) ^ ( \nu _ ( i ) ) ) ) ) ( mol dm ) ( ( N ) ( L ) ) General thermodynamic activity constant K 0 = ∏ j = 1 p a ( Y j ) η j ∏ i = 1 r a ( X i ) ν i ( displaystyle K_ ( 0 ) = ( \frac ( prod _ ( j = 1 ) ^ ( p ) a left ( mathrm ( Y ) _ ( j ) \right ) ^ ( eta _ ( j ) ) ) ( prod _ ( i = 1 ) ^ ( r ) a left ( mathrm ( X ) _ ( i ) \right ) ^ ( \nu _ ( i ) ) ) ) ) a ( X ) and a ( Y ) are activities of X and Y respectively. ( mol dm ) ( ( N ) ( L ) ) Equilibrium constant for gaseous reactions, using Partial pressures K p = ∏ j = 1 p p ( Y j ) η j ∏ i = 1 r p ( X i ) ν i ( displaystyle K_ ( p ) = ( \frac ( prod _ ( j = 1 ) ^ ( p ) p left ( mathrm ( Y ) _ ( j ) \right ) ^ ( eta _ ( j ) ) ) ( prod _ ( i = 1 ) ^ ( r ) p left ( mathrm ( X ) _ ( i ) \right ) ^ ( \nu _ ( i ) ) ) ) ) Pa ( ( M ) ( L ) ( T ) ) Logarithm of any equilibrium constant pK p K c = − log 10 ⁡ K c = ∑ j = 1 p η j log 10 ⁡ ( Y j ) − ∑ i = 1 r ν i log 10 ⁡ ( X i ) ( displaystyle mathrm ( p ) K_ ( c ) = - log _ ( 10 ) K_ ( c ) = sum _ ( j = 1 ) ^ ( p ) eta _ ( j ) log _ ( 10 ) left ( mathrm ( Y ) _ ( j ) \right ) - sum _ ( i = 1 ) ^ ( r ) \nu _ ( i ) log _ ( 10 ) left ( mathrm ( X ) _ ( i ) \right ) ) dimensionless dimensionless Logarithm of dissociation constant pK p K = − log 10 ⁡ K ( displaystyle mathrm ( p ) K = - log _ ( 10 ) K ) dimensionless dimensionless Logarithm of hydrogen ion ( H ) activity, pH pH pH = − log 10 ⁡ ( H + ) ( displaystyle ( ce ( pH = - log _ ( 10 ) ( H+ ) ) ) ) dimensionless dimensionless Logarithm of hydroxide ion ( OH ) activity, pOH pOH pOH = − log 10 ⁡ ( OH − ) ( displaystyle ( ce ( pOH = - log _ ( 10 ) ( OH ^ ( - ) ) ) ) ) dimensionless dimensionless Electrochemistry Notation for half - reaction standard electrode potentials is as follows. The redox reaction A + BX ↽ − − ⇀ B + AX ( displaystyle ( ce ( ( A ) + ( BX ) < = > ( B ) + ( AX ) ) ) ) split into : a reduction reaction : B + + e − ↽ − − ⇀ B ( displaystyle ( ce ( ( B+ ) + ( e ^ ( - ) ) < = > ( B ) ) ) ) and an oxidation reaction : A + + e − ↽ − − ⇀ A ( displaystyle ( ce ( ( A+ ) + ( e ^ ( - ) ) < = > ( A ) ) ) ) ( written this way by convention ) the electrode potential for the half reactions are written as E ⊖ ( A + A ) ( displaystyle E ^ ( ominus ) left ( ( ce ( A+ ) ) \vert ( ce ( A ) ) \right ) ) and E ⊖ ( B + B ) ( displaystyle E ^ ( ominus ) left ( ( ce ( B+ ) ) \vert ( ce ( B ) ) \right ) ) respectively. For the case of a metal - metal half electrode, letting M represent the metal and z be its valency, the half reaction takes the form of a reduction reaction : M + z + z e − ⇌ M. ( displaystyle mathrm ( M ) ^ ( + z ) + z mathrm ( e ) ^ ( - ) \rightleftharpoons mathrm ( M ). ) Quantity ( Common Name / s ) ( Common ) Symbol / s Defining Equation SI Units Dimension Standard EMF of an electrode E ⊖, E ⊖ ( X ) ( displaystyle E ^ ( ominus ), E ^ ( ominus ) left ( ( ce ( X ) ) \right ) ) Δ E ⊖ ( X ) = E ⊖ ( X ) − E ⊖ ( Def ) ( displaystyle Delta E ^ ( ominus ) left ( ( ce ( X ) ) \right ) = E ^ ( ominus ) left ( ( ce ( X ) ) \right ) - E ^ ( ominus ) left ( ( ce ( Def ) ) \right ) ) where Def is the standard electrode of definition, defined to have zero potential. The chosen one is hydrogen : E ⊖ ( H + ) = E ⊖ ( H + H ) = 0 ( displaystyle E ^ ( ominus ) left ( ( ce ( H+ ) ) \right ) = E ^ ( ominus ) left ( ( ce ( H+ ) ) \vert ( ce ( H ) ) \right ) = 0 ) V ( M ) ( L ) ( I ) ( T ) Standard EMF of an electrochemical cell E c e l l ⊖, Δ E ⊖ ( displaystyle E_ ( mathrm ( cell ) ) ^ ( ominus ), Delta E ^ ( ominus ) ) E c e l l ⊖ = E ⊖ ( C a t ) − E ⊖ ( A n ) ( displaystyle E_ ( mathrm ( cell ) ) ^ ( ominus ) = E ^ ( ominus ) left ( mathrm ( Cat ) \right ) - E ^ ( ominus ) left ( mathrm ( An ) \right ) ) where Cat is the cathode substance and An is the anode substance. V ( M ) ( L ) ( I ) ( T ) Ionic strength Two definitions are used, one using molarity concentration, I = 1 2 ∑ i = 1 N z i 2 ( X i ) ( displaystyle I = ( \frac ( 1 ) ( 2 ) ) sum _ ( i = 1 ) ^ ( N ) z_ ( i ) ^ ( 2 ) left ( ( \rm ( X ) ) _ ( i ) \right ) ) and one using molality, I = 1 2 ∑ i = 1 N z i 2 b i ( displaystyle I = ( \frac ( 1 ) ( 2 ) ) sum _ ( i = 1 ) ^ ( N ) z_ ( i ) ^ ( 2 ) b_ ( i ) ) The sum is taken over all ions in the solution. mol dm or mol dm kg ( N ) ( L ) ( M ) Electrochemical potential ( of component i in a mixture ) μ  ̄ i ( displaystyle ( \bar ( mu ) ) _ ( i ) , ! ) μ  ̄ i = μ − z e N A φ ( displaystyle ( \bar ( mu ) ) _ ( i ) = mu - zeN_ ( A ) phi , ! ) φ = local electrostatic potential ( see below also ) z = valency ( charge ) of the ion i J ( M ) ( L ) ( T ) Quantum chemistry Quantity ( Common Name / s ) ( Common ) Symbol / s Defining Equation SI Units Dimension Electronegativity χ Pauling ( difference between atoms A and B ) : χ A − χ B = ( e V ) − 1 / 2 E d ( A B ) − ( E d ( A A ) + E d ( B B ) ) / 2 ( displaystyle chi _ ( \rm ( A ) ) - chi _ ( \rm ( B ) ) = ( ( \rm ( eV ) ) ) ^ ( - 1 / 2 ) ( sqrt ( E_ ( \rm ( d ) ) ( ( \rm ( AB ) ) ) - ( E_ ( \rm ( d ) ) ( ( \rm ( AA ) ) ) + E_ ( \rm ( d ) ) ( ( \rm ( BB ) ) ) ) / 2 ) ) ) Mulliken ( absolute ) : χ = 10 − 3 ( 187 ( E I + E E A ) + 170 ) ( displaystyle chi = 10 ^ ( - 3 ) left ( 187 left ( E_ ( I ) + E_ ( EA ) \right ) + 170 \right ) , ) Energies ( in eV ) E = Bond dissociation E = Ionization E = Electron affinity dimensionless dimensionless References Jump up ^ http://goldbook.iupac.org/index.html Jump up ^ Quantitative Chemical Analysis ( 4th Edition ), I.M. Kolthoff, E.B. Sandell, E.J. Meehan, S. Bruckenstein, The Macmillan Co. ( USA ) 1969, Library of Congress Catalogue Number 69 10291 Jump up ^ Quantitative Chemical Analysis ( 4th Edition ), I.M. Kolthoff, E.B. Sandell, E.J. Meehan, S. Bruckenstein, The Macmillan Co. ( USA ) 1969, Library of Congress Catalogue Number 69 10291 Jump up ^ Physical chemistry, P.W. Atkins, Oxford University Press, 1978, ISBN 0 - 19 - 855148 - 7 Sources Physical chemistry, P.W. Atkins, Oxford University Press, 1978, ISBN 0 - 19 - 855148 - 7 Chemistry, Matter and the Universe, R.E. Dickerson, I. Geis, W.A. Benjamin Inc. ( USA ), 1976, ISBN 0 - 8053 - 2369 - 4 http://goldbook.iupac.org/index.html Chemical thermodynamics, D.J.G. Ives, University Cchemistry Series, Macdonald Technical and Scientific co. ISBN 0 - 356 - 03736 - 3. Elements of Statistical Thermodynamics ( 2nd Edition ), L.K. Nash, Principles of Chemistry, Addison - Wesley, 1974, ISBN 0 - 201 - 05229 - 6 Statistical Physics ( 2nd Edition ), F. Mandl, Manchester Physics, John Wiley & Sons, 2008, ISBN 978 - 0 - 471 - 91533 - 1 Further reading Quanta : A handbook of concepts, P.W. Atkins, Oxford University Press, 1974, ISBN 0 - 19 - 855493 - 1 Molecular Quantum Mechanics Parts I and II : An Introduction to QUANTUM CHEMISTRY ( Volume 1 ), P.W. Atkins, Oxford University Press, 1977, ISBN 0 - 19 - 855129 - 0 Thermodynamics, From Concepts to Applications ( 2nd Edition ), A. Shavit, C. Gutfinger, CRC Press ( Taylor and Francis Group, USA ), 2009, ISBN 978 - 1 - 4200 - 7368 - 3 Properties of matter, B.H. Flowers, E. Mendoza, Manchester Physics Series, J. Wiley and Sons, 1970, ISBN 978 - 0 - 471 - 26498 - 9 SI units Authority : International System of Units ( BIPM ) Base units ampere candela kelvin kilogram metre mole second Derived units with special names becquerel coulomb degree Celsius farad gray henry hertz joule katal lumen lux newton ohm pascal radian siemens sievert steradian tesla volt watt weber Other accepted units astronomical unit bar dalton day decibel degree of arc electronvolt hectare hour litre minute minute of arc neper second of arc tonne atomic units natural units See also Conversion of units Metric prefixes Proposed redefinitions Systems of measurement Book Retrieved from `` https://en.wikipedia.org/w/index.php?title=Defining_equation_(physical_chemistry)&oldid=784070157 '' Categories : Measurement Mathematical chemistry Chemical properties Physical chemistry Equations Talk Contents About Wikipedia Add links This page was last edited on 6 June 2017, at 08 : 57. 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Question: what do brackets in an chemical equation mean
Answer: chemical molecular formula