Ideal Solution MCQ - Practice Questions & Answers

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Quick Facts

Ideal Solution is considered one of the most asked concept.
15 Questions around this concept.

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Equimolal solutions in the same solvent have

same boiling point but different freezing point

same freezing point but different boiling point

same boiling and same freezing points

different boiling and different freezing points

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If liquids A and B form an ideal solution, the

enthalpy of mixing is zero

entropy of mixing is zero

free energy of mixing is zero

free energy as well as the entropy of mixing are each zero.

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Concepts Covered - 2

Ideal Solution

The solutions which obey Raoult’s law for the entire range of composition are called Ideal solutions.

In these solutions, the solute-solute and solvent-solvent interactions are almost similar to solute-solvent interactions (A-B = A-A or B-B interactions). Since the existing forces and the newly formed forces are almost identical, there is no enthalpy change in the mixing of these solutions i.e $\Delta H_{mix} = 0.$

There is no change in the volume during the mixing process i.e. $\Delta V_{mix} = 0.$ For example if 1 litre solutions each of liquid A and B are mixed to form an ideal solution, then the solution obtained has a volume equal to 2 litres.

The entropy of mixing is positive as new interactions are introduced into the solution which increases the randomness of the system and hence $\Delta S_{mix} > 0.$ The mixing process is spontaneous and hence $\Delta G_{mix} < 0.$

These solutions have vapor pressure as predicted by Raoult’s law.
$\\P_A=P{_{A}^{o}}X_A\\ P_B=P{_{B}^{o}}X_B\\ P_T=P_A+P_B$

Examples of Ideal solution

For the solutions to follow the ideal solution at all ranges of concentrations and temperatures then the molecular size of the liquids should be nearly the same.
For example:

CH₃OH + C₂H₅OH: Both these liquids are polar and have nearly the same size. Thus, this solution is an ideal solution.
C₂H₅Br₂ + C₂H₅Cl₂: Both these liquids are polar and have nearly the same size. Thus, this solution is an ideal solution.
C₂H₅Cl + C₂H₅Br: Both these liquids are polar and have nearly the same size. Thus, this solution is an ideal solution.
C₆H₆ + C₆H₅CH₃: Both these liquids are non-polar and have nearly the same size. Thus, this solution is an ideal solution.
C₂H₅Cl + C₂H₅I: Both these liquids are polar but the size difference between the molecules is large. Thus, this solution is not an ideal solution.