The above equation can be written as:
10
01
1
p – p  
p
 = 
2
1
2
 
 

n
n
n
 
2
2
1
2
since 







n
x
n
n
(1 26)
Here n1 and n2 are the number of moles of solvent and solute
respectively present in the solution For dilute solutions n2 < < n1,
hence neglecting n2 in the denominator we have
10
1
0
1
p
p
p

= 
2
1
n
n
(1 27)
or
10
1
0
1
 -  
 
p
p
p
= 
2
1
2
1
w  × 
 × w
M
M
(1