CHAPTER 9 MIXTURES
9.7 ACTIVITY OF ANUNCHARGEDSPECIES 271
components:
Substanceiin a gas mixture iDi(g)CRTlnai(g) (9.7.3)
Substanceiin a liquid or solid mixture iDiCRTlnai (9.7.4)
Solvent A of a solution ADACRTlnaA (9.7.5)
Solute B, mole fraction basis BDx;BCRTlnax;B (9.7.6)
Solute B, concentration basis BDc;BCRTlnac;B (9.7.7)
Solute B, molality basis BDm;BCRTlnam;B (9.7.8)
9.7.2 Activities and composition
We need to be able to relate the activity of componentito the mixture composition. We
can do this by finding the relation between the chemical potential of componenti in its
reference state and in its standard state, both at the same temperature. These two chemical
potentials,refi andi, are equal only if the mixture is at the standard pressurep.
It will be useful to define the following dimensionless quantity: