Question

Given:

Π = T R i M

R = 0.08206 L Atm/ mol Kelvin

Hypertonic saline (NS) 7.0% NaCl solutions (density = 1.056 g/mL) are considered mucoactive agents and thus are used to hydrate thick secretion (mucus) in order to make it easier to cough up and out (expectorate). Inhalation of hypertonic saline has also been shown to help in other respiratory prpblem, specifically bronchiolitis. Hypertonic saline is currently recommended by the Cystic Fibrosis Foundation as a primary part of a cystic fibrosis treatment regimen. What is the osmotic Pressure of this pertonic saline solution at 25 degrees celicus (C)?

Answer 1

Given:

Π = T R i M

R = 0.08206 L Atm/ mol Kelvin

the molarity of the 7.0% (m/v) NaCl solution?

M = # mol solute/1 L solution
7.0% (m/v) NaCl = 7.0 g NaCl/100 mL solution
       = 70 g NaCl/1 L solution
70 g NaCl = 70/58.5 mol = 1.18 mol
Thus, the solution is 1.18 M

Alternative thought:
7.0% (m/v) NaCl = 7.0 g NaCl/0.1 L solution
      = (7.0/58.5)/0.1 = 1.18 M

Temperature 25 degrees celicus (C)

T = 25 ^oC + 273 = 298 K

i = 2 (NaCl breaks into two particles)

M = 1.18 moles/L

R = 0.08206 L Atm/ mol Kelvin

T = 25 ^oC + 273 = 298 K

Π = T R i M

Π = 298×0.08206×2×1.18

Π = 57.71 atm

osmotic Pressure of this pertonic saline solution at 25 degrees celicus 57.71 atm