Osmotic pressure is the measure of the tendency of a solution to take in water by osmosis. It is directly proportional to its concentration (molarity) at constant temperature.
π = iMRT
π – osmotic pressure (atm), i-Van’t Hoff factor, M –concentration of solution (moles/L), R-0.0821 atm.L/mol.K, T – temperature (K)
A isotonic saline solution is prepared by dissolving 0.879g of NaCl in enough water to produce 140.0mL of solution. Calculate the osmotic pressure, in atmospheres of the solution at 25.0˚C.
NaCl moles = 0.879/58.44 = 0.0150 moles
Molarity = 0.0150/.140 = 0.107 moles/L
π = 2 x 0.107 moles/L x 0.0821Latm/mol K x 298K = 5.24 atm