For the rehydration therapy for cholera patients, the World Health Organization

ID: 695727 • Letter: F

Question

For the rehydration therapy for cholera patients, the World Health Organization (WHO) uses an aqueous solution made with 3.5 g NaCI/L, 2.5 g NaHCO,/L, 1.5 g KCIL and 20 g of glucose (GJ 1120.)Assuming that the ionic compounds break up fully into their ions (glucose is molecular), calculate the osmolarity of the solution. 16) 17) Calculate the freezing point of a solution that contains 50.0 g of sucrose dissolved in 200 g of water? The freezing point of a glucose solution is-32. In this solution how many grams of glucose are dissolved in each 100g of water? 18)

Explanation / Answer

16) It must be noted that for ionic compounds of the type MX (where M = cation and X = anion), 1 mole of MX will furnish 2 Osmoles of ions (since we will need to consider both M+ and X-). The volume of the solution is 1 L. Determine the number of Osmoles of the ionic and molecular compounds.

Compound

Molar Mass (g/mol)

Number of moles = (mass in grams)/(molar mass)

Number of Osmoles

NaCl

58.44

(3.5 g)/(58.44 g/mol) = 0.05989 mole

2*0.05989 = 0.11978

NaHCO3

84.007

(2.5 g)/(84.007 g/mol) = 0.02976 mole

2*0.02976 = 0.05952

KCl

74.5513

(1.5 g)/(74.5513 g/mol) = 0.02012 mole

2*0.02012 = 0.04024

Glucose

180.1559

(20.0 g)/(180.1559 g/mol) = 0.11101 mole

1*0.11101 = 0.11101

Total

0.33055

Osmolarity of the solution = (number of Osmoles in the solution)/(volume of the solution) = (0.33055 Osmole)/(1 L) = 0.33055 Osmol/L 0.330 Osmol/L (ans).