Question

1. What is the molar concentration of a solution that contains 10 grams of KCl in 500 ml of DI water? (MW of KCI = 74 g/mol) a. What is the osmolarity of this solution? b. What is the tonicity of this solution? c. What would happen to a normal red blood cell that was put into this solution?

Answer 1

Ans 1 :

a)

Mol KCl = mass / molar mass

= 10 g KCl / 74 g/mol

= 0.135 mol

Each mol KCl has two osmoles , number of osmoles here : 2 x 0.135 osmoles = 0.270 osmoles

Osmolarity = osmoles / volume (L)

putting values :

= 0.270 osmoles / 0.500 L

= 0.540 Osmoles/L

b)

The solution is hypertonic as its osmolarity is more than the isotonic solution.

c)

The red blood cells shrink when they are put into hypertonic solutions as they lose their water into the solution. So here when the red blood cell is put into this solution , the cells shrink.