Handbook of Solvents - George Wypych - ChemTech - Ventech!

512 Y. Y. Fialkov, V. L. Chumak
where:
m the number of component moles.
Mass fraction, P, equals to:
i= i
∑
P = g / g
i i
i=
1
where:
g mass of a component.
It is evident that for a solvent mixture, whose components do not interact:
∑ ∑ ∑
[9.17]
V = X = P =1 [9.18]
and expressed in percent
∑
∑
∑
V = X = P =
100 100 100 100
[9.19]
Fractions (percentage) [9.19] of mixed solvents, since they are calculated for initial
quantities (volumes) of components, are called analytical. In the overwhelming majority of
cases, analytical fractions (percentages) are used in the practice of mixed solvents application.
However, in mixed solvents A-B, whose components interact with formation of adducts,
AB, AB 2, it is possible to use veritable fractions to express their composition. For example,
if the equilibrium A+B ↔ AB establishes, veritable mole fraction of A component
equals to:
( )
N = m / m + m + m
[9.20]
A A A B AB
where:
mi number of moles of equilibrium participants
In the practice of mixed solvents application, though more seldom, molar, cM, and
molal, cm, concentrations are used. Correlations between these various methods of concentration
expression are shown in Table 9.1.
Table 9.1. Correlation between various methods of expression of binary solvent A-B
concentration (everywhere - concentration of component A)
Argument
Function
x V P cM cm
x VθB /( θA −σθV) PM B /( M A −σMP) cMθB /( 10 ρ cMσM)
3 − cmMB /( 10 cmMB) 3 +
V xθA /( σθx + θB)
PρB /( ρA −σ pP)
cMθ A /10 3
c M θ /( 10 θ c M θ )
3
+
m B A B m B A
P xM A /( σ Mx+ M B)
VρA /( σ pV + ρB)
cMMA /10 3 ρ cmMA /( 10 cmMA) 3 +
cM 10 3 ρx /( σ x M )
M + B 10 3 V / θA 10 3 ρP MA 3 3
/ 10 ρcm /( 10 + cmMA) 3 3 3 3 3
cm10 x / M ( 1 − x)
10 θ V / M θ ( 1 −V) 10 P / M ( 1 − P)
10 c /( 10 ρ−M
c )
B
B B A
A
M A M
σis the difference between the corresponding properties of components, i.e., σ y =y A-y B,ρis density, and θ is molar
volume.