Question

What is osmosis?

Answer 1

Hint: The phenomenon of osmosis was discovered by Pfeffer and it tells about the movement of a solvent across a semipermeable membrane. It is a special case of diffusion.

Complete step by step answer: Osmosis is the migration of solvent molecules from a hypotonic solution i.e. solution with lower concentration to a hypertonic solution i.e. solution with higher concentration through a semipermeable membrane to keep the concentrations equal.
Osmosis can also be defined through the concept of free energy levels of the solvent molecules. According to this solvent moves from its higher free energy level to lower free energy level.
It is generally of two types:
Exosmosis- It is the case when the water moves out of the cell due to the hypertonic solution present outside. It causes the protoplasm to shrink and leave the cell wall, making it flaccid. It is called plasmolysed cell and the phenomenon is called plasmolysis.
Endosmosis- It is the case when the water enters the cell due to the hypotonic solution present outside the cell. It is known as deplasmolysis and it helps in restoring the turgidity of cells.
Osmotic pressure is the pressure which must be applied to it in order to prevent the passage of solvent due to osmosis.
The factors that control osmosis are:
The concentration of the dissolved solutes in the solution.
The pressure difference between the solutions.

Note: Reverse osmosis involves applying additional pressure to the water so that it moves from hypertonic solution to hypotonic solution. By this method, salts can be removed from the saline water.