Question

$XY$ is the membrane / partition between two chambers 1 and 2 containing sugar solutions of concentration $\mathrm{c}_{1}$ and $\mathrm{c}_{2}\left(\mathrm{c}_{1}>\mathrm{c}_{2}\right) \mathrm{mol} \mathrm{L}^{-1}$. For the reverse osmosis to take place identify the correct condition} (Here $\mathrm{p}_{1}$ and $\mathrm{p}_{2}$ are pressures applied on chamber 1 and 2 )

• A. Membrane/Partition ; Cellophane, $\mathrm{p}_{1}>\pi$
• B. Membrane/Partition ; Porous. $\mathrm{p}_{2}>\pi$
• C. Membrane/Partition ; Parchment paper, $\mathrm{p}_{1}>\pi$
• D. Membrane/Partition : Cellophane, $\mathrm{p}_{2}>\pi$ Choose the correct answer from the options given below:

Hint:

Reverse osmosis requires the pressure in the chamber with higher concentration to be greater than the osmotic pressure.

Answer 1

The Correct Option is C

To understand the conditions for reverse osmosis, we need to consider the principle of osmosis and how reverse osmosis works.

Osmosis: Osmosis is the movement of solvent molecules through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration. This process occurs to equalize solute concentrations on both sides of the membrane.

Reverse Osmosis: Reverse osmosis is the process of forcing solvent molecules to move from a region of higher solute concentration to a region of lower solute concentration by applying external pressure that exceeds the osmotic pressure.

The osmotic pressure \(\pi\) is given by:

\(\pi = iCRT\)

Where:

• \(i\) is the van’t Hoff factor.
• \(C\) is the concentration of the solution.
• \(R\) is the ideal gas constant.
• \(T\) is the temperature in Kelvin.

In the question, Chamber 1 contains a higher concentration of sugar solution (\(c_1\)) than Chamber 2 (\(c_2\)), i.e., \(c_1 > c_2\).

To achieve reverse osmosis, the pressure applied on Chamber 1 should exceed the osmotic pressure:

\(p_1 > \pi\)

Since the correct option must satisfy this condition and mentions the type of membrane used, the correct answer is:

Membrane/Partition: Parchment paper, \(p_1 > \pi\)

Thus, to perform reverse osmosis, the pressure in Chamber 1 must be greater than the osmotic pressure using an appropriate membrane like parchment paper.