Question

A 1.17 solution of nacl is isotonic with 7.2 solution of glucose calculate the value of i of nacl

Answer 1

Both solution are isotonic with each other means the osmotic pressure of both solution would be same

Therefore,

$\pi _{NaCl} = \pi _{glucose}$

We known that,

Osmotic pressure (π) = i × C× R×T

Here i is van't hoff factor and C is concentration in moles/L

$C_{NaCl} = \frac{1.17}{58.5} = 0.02 M$

$C_{glucose} = \frac{7.2}{180} =  0.04 M$

$i_{NaCl} = \frac{0.04RT}{0.02RT} = 2$

Thus the value of i for NaCl =2