Name: Solid Solutions
Uploaded: 2019-07-19
Duration: 2 min 56 s
Description: Solutions can be categorized as solid, liquid, and gaseous based on the physical states of solvents and solutes. In this video, let's learn about solid solutions.

Question

Mention any three characteristics of an ideal solution. What does cause deviation from ideal behaviour?

Accepted Answer

The characteristics of an ideal solution are as follows.

1. Solution and its components obey Raoult's law : Each component belonging to an ideal solution and the solution itself obey Raoult's law. If two liquids A and B mix up together to form an ideal solution, then

$p_{A} = p_{A}^{0} χ_{A}, p_{B} = P_{B}^{0} χ_{B} and p = p_{A} + p_{B} = p_{A}^{0} χ_{A} + p_{B}^{0} χ_{B}$

where $p_{A}, p_{B}, p_{A}^{0}, p_{B}^{0}, χ_{A}, χ_{B}$ and $p$ have the same meaning as mentioned earlier.

2. The change in volume on mixing is zero : An ideal solution obeys the additivity rule, i.e., the total volume of the solution is equal to the sum of the volumes of its individual components. Technically, the partial molar volume of a component present in the solution is equal to its molar volume in pure state under identical conditions of temperature and pressure. Thus, there will be no change in volume on mixing the components, i.e., $∆ V_{mixing} = 0$

This is because the nature of molecular interaction forces does not change significantly when the components forming an ideal solution are mixed together.

3. The change in enthalpy on mixing is zero : When the components forming an ideal solution are mixed together, no heat is evolved or absorbed and the enthalpy of the system remains constant. Thus, there is no change in enthalpy on mixing the components of an ideal solution, i.e., $∆ H_{mixing} = 0$

This is again due to the fact that on mixing the components forming an ideal solution, the nature of molecular interaction forces does not change significantly. Hence, no heat is evolved or absorbed on forming the solution.

The term deviation of gases tells us about the deviation in the behaviour of real gases from the ideal behaviour of gases.
The reason behind the deviation of gases from the ideal behaviour is few assumptions of kinetic theory.
The assumptions are as follows:
The first assumption is that the particles are point sized. This means that the particles have no volume as compared to the volume of the vessel.
The second assumption is that there is no force of attraction between the molecules of gas, hence the collisions of molecules are treated as perfectly elastic.
Due to these two assumptions we can see the deviations from the ideal behaviour of gases.

Mention any three characteristics of an ideal solution. What does cause deviation from ideal behaviour?

Important Questions on Solutions

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