Question

1.2% nacl solution is isotonic with 7.2% glucose solution what is vant hoff factor

Answer 1

Answer: 2

Explanation:

Isotonic solutions are those solutions which have the same osmotic pressure.  If osmotic pressures are equal at the same temperature, concentrations must also be equal.

$\pi =CRT$ for non electrolytes such as glucose

$\pi =iCRT$ for electrolytes such as $NaCl$

$\pi$ = osmotic pressure

C= concentration

R= solution constant

T= temperature

i= vant hoff factor

Thus: $C_{glucose}=iC_{NaCl}$ where concentration is in molarity.

For glucose solution: 7.2 g of glucose is dissolved in 100 ml of solution.

For NaCl solution: 1.2 g of NaCl is dissolved in 100 ml of solution.

$Molarity=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{volume of solution in ml}}$

$C_{glucose}=\frac{7.2\times 1000}{180}\times {100}=0.4M$

$C_ {NaCl}=\frac{1.2\times 1000}{58.5}\times 100}=0.20M$

As $C_{glucose}=i\times C_{NaCl}$

$0.4=i\times 0.20$

$i= 2$

Thus vant hoff factor for $NaCl$ is 2.