Question

Intravenous, or IV, solutions used in medicine must exert the same osmotic pressure as blood to prevent a net flow of water into or out of the blood cells. The proper concentration for an intravenous NaCl solution is 0.90 g NaCl per 100. mL of solution (sometimes referred to as 0.90% m/v). If the van't Hoff factor of NaCl is ?=1.8, what is the osmotic pressure of blood at body temperature, 37 ∘C?

Answer 1

Given,

concentration for an intrvenous NaCl solution = 0.90 g NaCl / 100. mL solution

van't hoff factor of NaCl "i" = 1.8

Temperature(T) = 37 ^oC + 273.15 = 310.15 K

Convering the given concentration from( g/mL) of solution to (mole/L) of solution,

= (0.90 g NaCl / 100. mL solution) x ( 1 mol / 58.44 g) x ( 1000 mL /1 L)

= 0.154 mol/L of NaCl solution

The formula of osmotic pressure,

Osmotic pressure() = i x M x R x T

Here, M is the molarity of solution

R = 0.08206 L.atm/mol.K

T = Temperature in Kelvin.

Substituting the known values,

Osmotic pressure() = 1.8 x 0.154 mol/L x 0.08206 L.atm/mol.K x 310.15 K

Osmotic pressure() = 7.05 atm

Thus, osmotic pressure of blood is 7.05 atm