Question

Calculate osmotic pressure of blood at 298 K given that blood freezes at 272.44 K and a solution of 3g of urea in 250 g water freezes at 272.63 K. Take freezing point of water as 273 K.

Answer 1

We know,

To calculate molarity of blood, we need to just calculate K_f of water from urea solution

Molality of blood

The osmotic pressure of blood is

since, Colligative properties are defined for dilute solution ⇒ Molarity = Molality

π = cRT

= 0.303 x 0.0821 x 298 

= 7.4 atm.