文档介绍：Chapter 9
Solutions
position
Solutions
()*
A solution is a homogeneous mixture; that is, a solution is a one-phase system with more than ponent.
The mole fraction xi of species i is defined by
()
The (molar) concentration (or volume concentration) ci of species i is defined by
The mass concentration i of species i in a solution of volume V is defined by
()*
Physical Chemistry
position
Solutions
The molarity is the molar concentration of a species for liquid solutions in moles per liter (dm3).
The molarity mi of species i in a solution is defined by
The solute molarity mB is
()*
Solution
Solvent (A)
Solute (B)
()
Physical Chemistry
Partial Molar Quantities
Solutions
The star indicates a property of a pure substance or a collection of pure substances.
()
Partial Molar Volumes
0 25 50 75 100
V (ethanol)/cm3
100
99
98
97
96
75 50 25 0
V (H2O)/cm3
V /cm3
Addition of cm3 of water to cm3 of ethanol at 20 oC and 1 atm gives a solution of cm3 (Fig. , left).
Physical Chemistry
Partial Molar Quantities
Solutions
0 25 50 75 100
V (ethanol)/cm3
100
99
98
97
96
75 50 25 0
V (H2O)/cm3
V /cm3
(1) different intermolecular forces
(2) different packing of molecules
(different sizes and shapes of the molecules being mixed)
()
The total differential of V
()
Physical Chemistry
Partial Molar Quantities
Solutions
()
The partial molar volume
()*
Physical Chemistry
nj: the amount of a substance j
nij: the amount of all other substances present are constant
Partial Molar Quantities
Solutions
The partial molar volume
()*
()
Equation () es
Physical Chemistry
V(a)
V(b)
x
V
The partial molar volume is the slope of the graph of the total volume as the amount of j is changed, P, T, amount of ponents being constant
Partial Molar Quantities
Solutions
The partial molar volume
()*
The partial molar volume of a pure substance is equal to its molar volume.
(