A solution of acetone in ethanol

Question

Which one of the following is not correct for an ideal solution?

Answer 1

A solution of acetone in ethanol exhibits a positive deviation from Raoult's law. Let's understand why this is the case:

Understanding Raoult's Law: Raoult's law states that the vapor pressure of a solution is dependent on the vapor pressure of each chemical component and the mole fraction of the component present in the solution. Mathematically, it is represented as: P_{\text{solution}} = x_1 P_1^0 + x_2 P_2^0, where x_1 and x_2 are the mole fractions of components 1 and 2, and P_1^0 and P_2^0 are their respective vapor pressures.
Deviations from Raoult's Law: There are two types of deviations:
- Positive Deviation: Occurs when the interactions between different molecules (A-B) are weaker than the interactions between similar molecules (A-A or B-B). This results in a higher vapor pressure than predicted by Raoult’s law.
- Negative Deviation: Occurs when the interactions between different molecules are stronger, leading to a lower vapor pressure.
Application to Acetone and Ethanol: In the case of acetone and ethanol:
- Both acetone and ethanol have strong hydrogen bonds in their pure forms (ethanol especially).
- When mixed, the hydrogen bond interactions between ethanol molecules and the dipole-induced interactions with acetone are weaker than the hydrogen bonds present in pure ethanol or pure acetone solutions.
- Therefore, the solution has a higher vapor pressure than expected, showing positive deviation.
Conclusion: The correct answer is that the solution of acetone in ethanol shows a positive deviation from Raoults law.

Answer 2

A solution of acetone in ethanol exhibits a positive deviation from Raoult's law. Let's understand why this is the case:

Understanding Raoult's Law: Raoult's law states that the vapor pressure of a solution is dependent on the vapor pressure of each chemical component and the mole fraction of the component present in the solution. Mathematically, it is represented as: P_{\text{solution}} = x_1 P_1^0 + x_2 P_2^0, where x_1 and x_2 are the mole fractions of components 1 and 2, and P_1^0 and P_2^0 are their respective vapor pressures.
Deviations from Raoult's Law: There are two types of deviations:
- Positive Deviation: Occurs when the interactions between different molecules (A-B) are weaker than the interactions between similar molecules (A-A or B-B). This results in a higher vapor pressure than predicted by Raoult’s law.
- Negative Deviation: Occurs when the interactions between different molecules are stronger, leading to a lower vapor pressure.
Application to Acetone and Ethanol: In the case of acetone and ethanol:
- Both acetone and ethanol have strong hydrogen bonds in their pure forms (ethanol especially).
- When mixed, the hydrogen bond interactions between ethanol molecules and the dipole-induced interactions with acetone are weaker than the hydrogen bonds present in pure ethanol or pure acetone solutions.
- Therefore, the solution has a higher vapor pressure than expected, showing positive deviation.
Conclusion: The correct answer is that the solution of acetone in ethanol shows a positive deviation from Raoults law.

The Correct Option is D