Question

In a very ideal imaginary condition, a sample of ice was taken, and its osmotic pressure was found to be 0.274 atm at 300 K (density = 1g/mL). Thus, number of water units attached to one water unit is ________ .

• A. 4
• B. 3
• C. 6
• D. 5

Answer 1

The correct option is A 4

The expression for calculating the concentration C from the osmotic pressure $\pi$ is as given below:
$iC=\frac{\pi }{RT}$
Here, i is the Van't Hoff's factor, R is the ideal gas constant and T is temperature.
Substituting the values in the above expression:
$iC=\frac{0.274atm}{0.0821L.atm.mol.K\times 300K}=0.011125mol/L$......(1)
But, the density of ice is 1 g.mL or 1000 g/L.
It's concentration is $\frac{1000g}{18g/mol\times 1L}=55.5mol/L$......(2)
From (1) and (2),
$i=\frac{55.5}{0.011125}=4000.$