Question

Which of the following is an ideal solution
A) Water + Ethanol
B) Chloroform + carbon tetrachloride
C) Benzene + Toluene
D) Water + Hydrochloric acid

Answer 1

An ideal solution, also known as an ideal mixture, is a chemical solution in which the gas phase possesses thermodynamic characteristics that are similar to those of a combination of ideal gases. By definition, the enthalpy of mixing is zero, and the volume change on mixing is also zero; the closer the enthalpy of mixing is to zero, the more "ideal" the solution's behaviour becomes. The solution's vapour pressure obeys either Raoult's law or Henry's law (or both), and each component's activity coefficient (which gauges departure from ideality) equals one.

Complete answer:
There have been several proposed definitions of an ideal solution. The most basic definition is that an ideal solution is one in which each component I for all compositions obeys Raoult's rule ${{p}_{i}}={{x}_{i}}p_{i}^{*}$ . Component i's vapour pressure above the solution is ${{p}_{i}}$ , its mole fraction is ${{x}_{i}}$ , and the pure substance i's vapour pressure at the same temperature is ${{p}_{i}}*$ .
Due to the existence of hydrogen bonding in the ethyl alcohol solution and water molecules, a solution of ethyl alcohol and water deviates from Raoult's law in a positive way.
Chloroform + carbon tetrachloride deviates from Raoult's law in a favourable way.
Water + HCl is a non-ideal solution that deviates from Raoult's law in a negative way.
A-B interactions are almost comparable to A-A and B-B interactions in a Benzene-toluene combination because of the tiny difference in the two compounds, i.e., they differ only by one $C{{H}_{2}}$ group. As a result, Raoult's law will not be broken.

Note:
Chemical thermodynamics and its applications, such as the utilisation of colligative characteristics, are based on the concept of an ideal solution. The ideality of solutions is similar to that of gases, with the significant exception that intermolecular interactions in liquids are strong and cannot be ignored as easily as they can in ideal gases. Instead, we assume that all of the molecules in the solution have the same mean strength of interactions.