Question

If a solution contains 0.1 M glucose along with 0.15 M NaCl, what is the osmolarity of this solution?

A) 350 mOsm

B) 0.4 M

C) 0.25 M

D) 400 mOsm

E) 250 mOsm

Answer 1

D) 400 mOsm. The osmolarity of a solution with 0.1 M glucose and 0.15 M NaCl is calculated by adding the contribution of both solutes.

Step-by-step explanation:

To calculate the osmolarity of a solution containing glucose and NaCl, we must consider the individual contribution of each solute and the fact that NaCl dissociates into two ions, Na+ and Cl-, when dissolved. The osmolarity of the glucose solution, being a non-electrolyte, equals its molarity, so it contributes 0.1 osmol/L. Sodium chloride, an electrolyte, will dissociate into two particles per formula unit, hence its contribution is 0.15 M x 2 = 0.3 osmol/L. By adding these contributions, we find the total osmolarity of the solution:

Total osmolarity = Osmolarity of glucose + Osmolarity of NaCl = 0.1 osmol/L + 0.3 osmol/L = 0.4 osmol/L

Since 1 osmol/L is equivalent to 1000 milliosmoles per liter (mOsm/L), the solution has an osmolarity of 400 mOsm/L, which corresponds to option D.Glucose contributes 0.1 osmol/L, while NaCl dissociates into two ions, contributing 0.3 osmol/L, totalling 0.4 osmol/L or 400 mOsm/L, which is answer D.