mixture of ethanol and acetic acid will show which type of deviation and mixture of acetone and aniline show which type of deviation

When we look at mixtures of different substances, we often encounter concepts like positive and negative deviations from Raoult's Law. These deviations help us understand how the properties of a mixture differ from those of its pure components. Let's break down the two mixtures you've mentioned: ethanol and acetic acid, and acetone and aniline.

Mixture of Ethanol and Acetic Acid

The combination of ethanol and acetic acid typically exhibits a negative deviation from Raoult's Law. This occurs because the interactions between the molecules of ethanol and acetic acid are stronger than the interactions between the molecules of each substance in their pure forms. When these two compounds mix, hydrogen bonding plays a significant role. Ethanol can form hydrogen bonds with acetic acid, leading to a more stable mixture than what would be expected based solely on their individual vapor pressures.

Why Negative Deviation?

• Stronger Intermolecular Forces: The hydrogen bonds formed between ethanol and acetic acid are stronger than the hydrogen bonds in pure ethanol or the dipole-dipole interactions in pure acetic acid.
• Lower Vapor Pressure: Because of these stronger interactions, the vapor pressure of the mixture is lower than predicted, indicating a negative deviation.

Mixture of Acetone and Aniline

On the other hand, when we mix acetone and aniline, we usually observe a positive deviation from Raoult's Law. This is primarily due to the fact that the interactions between acetone and aniline molecules are weaker than the interactions within each of the pure substances. Acetone is a polar aprotic solvent, while aniline is a polar protic solvent. When mixed, the hydrogen bonding that occurs in aniline is disrupted, leading to a situation where the overall intermolecular forces in the mixture are less than those in the pure components.

Understanding Positive Deviation

• Weaker Intermolecular Forces: The interactions between acetone and aniline do not compensate for the strong hydrogen bonds present in pure aniline.
• Higher Vapor Pressure: As a result, the vapor pressure of the mixture is higher than what would be expected based on the individual vapor pressures of acetone and aniline, indicating a positive deviation.

Summary of Deviations

In summary, the mixture of ethanol and acetic acid shows a negative deviation due to stronger intermolecular interactions, while the mixture of acetone and aniline demonstrates a positive deviation because of weaker interactions. Understanding these deviations is crucial for predicting the behavior of mixtures in various chemical processes, such as distillation and extraction.