1 mole of glucose and 1 mole NaCl are dissolved in 1 liter o

1 mole of glucose and 1 mole NaCl are dissolved in 1 liter of water. The resulting osmolarity of the solution is.

A. 1 osmoles

B. 2 osmoles

C. 3 osmoles

D. 4 osmoles

E. not enough info to tell

Solution

Ans. Osmolarity is the number of osmoles of solute per liter of solution.

Osmole is the number of moles of a solute that contributes to osmolarity of the solution.

For an electrolyte (produces two or more ions in aqueous solution), number of osmoles is equal to number if ions produced per mol electrolyte. For example,1 mol NaCl that produces 2 ions in aqueous solution is equivalent to 2 osmoles. For non-electrolyte, 1 mol compound is equivalent to 1 osmole.

Given,

            Moles of NaCl = 1 mol

            Moles of glucose = 1 mol

            Volume of solution = 1 L

Now,

Total osmoles in solution = Osmoles of NaCl + Osmoles of glucose

                                    = 1 x 2 osmole + 1 osmole = 3 osmoles

Osmolarity of solution = total osmoles in solution/ total volume of solution

                                    = 3 osmol / 1L

                                    = 3 osmol/L = 3 osmoles

Hence, correct option: C