Question

What are the conditions for a solution to be ideal?

Answer 1

Raoult's Law only works for ideal solutions. An ideal solution is defined as one which obeys Raoult's Law. "An ideal solution shows thermodynamic mixing characteristics identical to those of ideal gas mixtures [except] ideal solutions have intermolecular interactions equal to those of the pure components."

Answer 2

Answer:

1) the enthalpy of mixing of two components should be zero

2) the volume of mixing is equal to zero

3) obey the Raoult's law

Explanation:

An ideal solution has a few characteristics. First, the enthalpy of mixing of two components should be zero. It is due to the intermolecular forces of attraction and repulsion in the solution is unchanged on mixing the pure components to form an ideal solution. In other words, there is neither absorption nor evolution of heat during mixing the liquids. Hence, the heat change on mixing Δ mixing H in solution should be zero.

Second, the volume of the mixing is equal to zero. It is because the total volume of the solution is exactly the same as the sum of the volume of the components before the mixing. The solutions tend to become ideal when they are diluted. Hence, there is no change in volume on mixing or Δ mixing V is zero.

Third, the most important characteristic is an ideal solution must obey Raoult’s law. Raoult’s law is a chemical law that states that the vapour pressure in a solution is equal or identical to the vapour pressure of the pure solvent multiplied by its mole fraction in the solution. It also can be written as;

Psolution =Psolvent0 Xsolvent

Psolution  = vapour pressure of the solution

Psolvent0   =  vapour pressure of the pure solvent

Xsolvent   = mole fraction of the solvent