Question 11.12: CALCULATING THE OSMOTIC PRESSURE OF A SOLUTION The total con...
CALCULATING THE OSMOTIC PRESSURE OF A SOLUTION
The total concentration of dissolved particles inside red blood cells and in the surrounding plasma is approximately 0.30 M, and the membrane surrounding the cells is semipermeable. What would the maximum osmotic pressure in atmospheres inside the cells be if the cells were removed from blood plasma and placed in pure water at 298 K?
STRATEGY
If red blood cells were removed from plasma and placed in pure water, water would pass through the cell membrane, causing a pressure increase inside the cells. The maximum amount of this pressure would be
\Pi = MRT
where M = 0.30 mol/L , R = 0.082 06 (L · atm)/(K · mol), T = 298 K.
\Pi = \left(0.30 \frac{mol}{L}\right) \left(0.082 06\frac{L · atm}{K · mol} \right)(298 K) = 7.3 atm
In fact, red blood cells rupture if the pressure differential across their membrane is greater than 5 atm, so the cells would burst if placed in pure water.