A solution of acetone in ethnol

Options

A. Shows a negative deviation for Raoult's law
B. Shows a positive deviation from Raoult's law
C. Behaves like a near ideal solution
D. Obeys Raoult's law

Answer

To solve the question regarding the behavior of a solution of acetone in ethanol in relation to Raoult's law, we can follow these steps:

### Step 1: Understand Raoult's Law
Raoult's law states that the vapor pressure of a solution is directly proportional to the mole fraction of the solvent in the solution. The formula can be expressed as:
\[ P = P_A^0 \cdot X_A + P_B^0 \cdot X_B \]
where:
- \( P \) is the vapor pressure of the solution,
- \( P_A^0 \) and \( P_B^0 \) are the vapor pressures of the pure components A and B,
- \( X_A \) and \( X_B \) are the mole fractions of components A and B in the solution.

### Step 2: Identify the Components
In this case, the components are:
- A = Acetone (C3H6O)
- B = Ethanol (C2H5OH)

Both acetone and ethanol are polar solvents.

### Step 3: Determine the Nature of the Solution
Since both acetone and ethanol are polar, they are expected to mix well. However, the interaction between the molecules of acetone and ethanol may differ from the interactions between the molecules of the pure substances.

### Step 4: Analyze Deviations from Raoult's Law
- **Positive Deviation**: This occurs when the vapor pressure of the solution is higher than what Raoult's law predicts. This typically happens when the intermolecular forces between different components are weaker than those in the pure components.
- **Negative Deviation**: This occurs when the vapor pressure of the solution is lower than predicted by Raoult's law, often due to stronger intermolecular forces in the mixture.

### Step 5: Conclusion
In the case of a solution of acetone in ethanol, the interactions between acetone and ethanol are weaker than the interactions in the pure substances. Therefore, the solution exhibits a positive deviation from Raoult's law.

### Final Answer
The solution of acetone in ethanol shows **positive deviation from Raoult's law**.

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