Question

Which of the following is correct for an ideal solution?

• A. Raoult's law is obeyed for entire concentration range and temperatures
• B. $\Delta H_{mix}=0$
• C. $\Delta V_{mix}=0$
• D. $\Delta S_{mix}=0$

Answer 1

Answer: (A), (B), (C)

$\Delta V_{mix}=0$

An ideal solution can be obtained by mixing a solute and a solvent which consist of similar molecular structure and size. If we take two substances X and Y and mix them we will see that there are several intermolecular forces that exist between them.

For example,

• X and X experience intermolecular forces of attraction.
• Y and Y experience intermolecular forces of attraction.
• X and Y experience intramolecular forces of attraction.

Here, when the intermolecular forces of attraction are the same or equal, it gives us an ideal solution.
The enthalpy of solution is zero. If the enthalpy of the solution gets closer to zero it is more likely to show an ideal behaviour. $\Delta H_{mix}=0$
The volume of mixing is also zero. $\Delta V_{mix}=0$