Question

Which condition is not satisfied by an ideal solution?

• A. ${∆}_{\mathrm{mix}}\mathrm{H}=0$
• B. ${∆}_{\mathrm{mix}}\mathrm{V}=0$
• C. ${∆}_{\mathrm{mix}}\mathrm{S}=0$
• D. Obeyance of Raoult's law

Answer 1

The correct option is C

${∆}_{\mathrm{mix}}\mathrm{S}=0$

Explanation for correct option:

C. ${∆}_{\mathrm{mix}}\mathrm{S}=0$

Ideal solution:

• “The solutions which obey Raoult’s law over the entire range of concentration are known as ideal solutions.”
• "The ideal solutions have two other important properties. The enthalpy of mixing of the pure components to form the solution is zero and the volume of mixing is also zero, i.e.,
• ${∆}_{\mathrm{mix}}\mathrm{H}=0$ and ${∆}_{\mathrm{mix}}\mathrm{V}=0$

The condition which is not satisfied by the ideal solution is the entropy of mixing the pure components is zero, i.e. ${∆}_{\mathrm{mix}}\mathrm{S}=0$.

Explanation for incorrect options:

The two conditions that satisfy the ideal solutions are ${∆}_{\mathrm{mix}}\mathrm{H}=0$ and ${∆}_{\mathrm{mix}}\mathrm{V}=0$ and also it obeys Roult's law. Thus, options A, B, and D are incorrect.

Hence, the correct option is C i.e. ${∆}_{\mathrm{mix}}\mathrm{S}=0$.