Physical Chemistry of Solutions Flashcards for NEET — 20 cards

First 8 of 20 Physical Chemistry of Solutions flashcards

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1. Card 1 of 20

   Which concentration terms are independent of temperature and which are dependent?

   Hint: Volume changes with temperature, mass does not.

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   Answer

   Temperature Independent: Molality ($m$), Mole fraction ($x$), Mass percentage (w/w). Temperature Dependent: Molarity ($M$), Volume percentage (v/v), Mass by volume percentage (w/v).

2. Card 2 of 20

   State Henry's Law regarding the solubility of a gas in a liquid.

   Hint: $K_H$ is Henry's law constant.

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   Answer

   Higher the value of $K_H$ at a given pressure, lower is the solubility of the gas in the liquid.

3. Card 3 of 20

   State Raoult's Law for a solution of volatile liquids.

   Hint: $p_1^0$ is the vapour pressure of the pure component.

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   Answer

   For a solution of volatile liquids, the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution. $p_1 = p_1^0 x_1$

4. Card 4 of 20

   What are the thermodynamic conditions for an Ideal Solution?

   Hint: Intermolecular attractive forces between A-A and B-B are nearly equal to A-B.

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   Answer

   1. It obeys Raoult's law over the entire range of concentration. 2. Enthalpy of mixing: $\Delta_{mix}H = 0$ 3. Volume of mixing: $\Delta_{mix}V = 0$

5. Card 5 of 20

   Describe the intermolecular forces and volume change for a solution showing Positive Deviation from Raoult's Law. Give an example.

   Hint: Weaker forces mean molecules escape easily, increasing vapour pressure.

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   Answer

   A-B interactions are WEAKER than A-A and B-B interactions. $\Delta_{mix}V > 0$ and $\Delta_{mix}H > 0$ (endothermic). Example: Ethanol + Acetone or Carbon disulphide + Acetone.

6. Card 6 of 20

   What is the van't Hoff factor ($i$) conceptually?

   Hint: $i$ corrects the colligative properties for electrolytes.

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   Answer

   $i = \frac{\text{Normal molar mass}}{\text{Abnormal molar mass}} = \frac{\text{Observed colligative property}}{\text{Calculated colligative property}}$ It accounts for the extent of dissociation or association of a solute in solution.

7. Card 7 of 20

   What are Azeotropes (Azeotropic Mixtures)?

   Hint: Constant boiling mixtures.

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   Answer

   Binary mixtures having the same composition in liquid and vapour phase and boil at a constant temperature. Their components cannot be separated by fractional distillation.

8. Card 8 of 20

   Which type of non-ideal solution forms a Minimum Boiling Azeotrope?

   Hint: High vapour pressure (positive deviation) means it boils at a lower temperature.

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   Answer

   Solutions showing a large POSITIVE deviation from Raoult's law form minimum boiling azeotropes at a specific composition (e.g., 95% ethanol-water mixture).