Question

Two solutions A and B are separated by a semipermeable membrane. If liquid flows from A to B then
A. A is less concentrated than B
B. A is more concentrated than C
C. Both have the same concentration
D. None of these

Answer 1

Hint: The osmosis process is spontaneous and occurs to maintain the balance in the concentration of the solution. The solution tends to be dilute (less concentrated) or pure (without any mixture or solute particle) as much as possible.

Complete Step by Step Answer:
Let us take two solutions in one beaker separated through a semipermeable membrane, one solution containing fewer solute particles (less concentrated or dilute) and the other containing a large number of solute particles (more concentrated).

It is very interesting to know that a semi-permeable membrane only allows the passage of solvent molecules from the solution but not solute. Now the solvent of the solution which is the less concentrated move towards the solution which is highly concentrated to make it dilute through a semipermeable membrane. And this process is known as osmosis.

As solvent molecules move toward the highly concentrated solution thus we fit the piston on the highly concentrated solution and push it until osmosis stops. Thus, the pressure we apply to stop the osmosis process is equal to the force with which solvent molecules move towards a concentrated solution. This pressure which we applied is known as osmotic pressure.

Now if liquid (solvent) moves from A to B it means A is moving toward B through a semi-permeable membrane to dilute B. Thus, we can say B is highly concentrated and A is less concentrated. The solvent of A is applying force on solution B which is equal to osmotic pressure.

It was first derived by Dutch chemist, Jacobus and given as
\[p\text{ }=\text{ }cRT\], p is osmotic pressure, c is concentration of solute molecules in moles per litre, R is gas constant, and T is temperature in Kelvin.
\[Or~p/c\text{ }=\text{ }RT\]
Thus, the correct option is A.

Note: When a solute is added to a solvent (generally water) it gives out a solution. Now if in any solution the number of moles of solute is present in a large amount then the solution is concentrated, otherwise dilute or less concentrated. An osmosis process occurs due to the difference in concentration between two solutions.