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Question
Explain the phenomenon of osmosis.
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Solution
- The net spontaneous flow of solvent molecules into the solution or from a more dilute solution to a more concentrated solution through a semipermeable membrane is called osmosis.
- When a solution and pure solvent or two solutions of different concentrations are separated by a semipermeable membrane, the solvent molecules pass through the membrane. However, the rate of passage of solvent molecules into the solution or from a more dilute solution to a more concentrated solution is found to be greater than the rate in the reverse direction. This is favourable since the vapour pressure of the solvent is greater than that of the solution.
- As a result of osmosis, the amount of liquid on the pure solvent side or more dilute solution side decreases. Consequently, the amount of liquid on the other side increases. This results in a decrease of the concentration of the solution.
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| Column I | Column II |
| (i) Saturated solution | (a) Solution having same osmotic pressure at a given temperature as that of given solution. |
| (ii) Binary solution | (b) A solution whose osmotic pressure is less than that of another. |
| (iii) Isotonic solution | (c) Solution with two components. |
| (iv) Hypotonic solution | (d) A solution which contains maximum amount of solute that can be dissolved in a given amount of solvent at a given temperature. |
| (v) Solid solution | (e) A solution whose osmotic pressure is more than that of another. |
| (vi) Hypertonic solution | (f) A solution in solid phase. |
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