is . ˚C for water) and the depression in freezing point (for molal solution the depression in freezing point is . ˚C for water), the magnitude of osmotic pressure is large. The osmotic pressure can be measured at room temperature enables to determine the molecular mass of biomolecules which are unstable at higher temperatures.
Even for a very dilute solution, the osmotic pressure is large. Isotonic solutions Two solutions having same osmotic pressure at a given temperature are called isotonic solutions. When such solutions are separated by a semipermeable membrane, solvent flow between one to the other on either direction is same, i.e. the net solvent flow between the two isotonic solutions is zero.
Figure . Isotonic solutions The osmotic pressure of the blood cells is approximately equal to atm at ˚C. The intravenous injections should have same osmotic pressure as that of Unit Unit - - - - the blood (isotonic with blood). If the Intravenous solutions are too dilute that is hypotonic, the solvent from outside of the cells will flow into the cell to normalise the osmotic pressure and this process which is called hemolysis, causes the cells to burst.
On the other hand, if the solution is too concentrated, that is hypertonic, the solvent molecules will flow out of the cells, which causes the cells to shrink and die. For this reason, the Intravenous fluids are prepared such they are isotonic to blood ( . % mass/ volume sodium chloride solution). .
Reverse osmosis (RO): Let us consider the experimental setup (Figure . ) discussed in the osmosis. The pure water moves through the semipermeable membrane to the NaCl solution due to osmosis. This process can be reversed by applying pressure greater than the osmotic pressure to the solution side.
Now the pure water moves from the solution side to the solvent side and this process is called reverse osmosis. It can be defined as a process in which a solvent passes through a semipermeable membrane in the opposite direction of osmosis, when subjected to a hydrostatic pressure greater than the