Anazeotropic mixture of two liquid has a boiling point higher than either of them when it :

Options

A. shows positive deviation from Raoult's law
B. shows negative deviation from Raoult's law
C. shows ideal behaviour
D. is saturated

Answer

To solve the question regarding the boiling point of an azeotropic mixture of two liquids, we need to understand the concept of azeotropes and how they behave in terms of boiling points. Here’s a step-by-step solution:

### Step 1: Understand Azeotropes
An azeotropic mixture is a mixture of two or more liquids that has a constant boiling point and composition throughout the distillation process. This means that the vapor produced has the same composition as the liquid mixture.

**Hint:** Recall that azeotropes can either have a boiling point higher or lower than the individual components.

### Step 2: Identify the Type of Azeotrope
Azeotropes can be classified into two types based on their boiling points:
- Maximum boiling azeotropes: The boiling point of the mixture is higher than that of either component.
- Minimum boiling azeotropes: The boiling point of the mixture is lower than that of either component.

**Hint:** Think about how the interactions between different molecules affect the boiling point.

### Step 3: Analyze the Given Statement
The question states that the azeotropic mixture has a boiling point higher than either of the components. This indicates that we are dealing with a maximum boiling azeotrope.

**Hint:** Consider what conditions lead to a higher boiling point in mixtures.

### Step 4: Relate to Raoult’s Law
For a maximum boiling azeotrope, the mixture exhibits negative deviation from Raoult's law. This means that the intermolecular forces between different molecules (A and B) are stronger than those in the pure components (A-A or B-B).

**Hint:** Remember that negative deviation occurs when the interactions between different components are stronger than those in the pure substances.

### Step 5: Conclusion
Therefore, the condition for an azeotropic mixture to have a boiling point higher than either of the components is that it must be a maximum boiling azeotrope, which occurs due to negative deviation from Raoult's law.

**Final Answer:** The azeotropic mixture has a boiling point higher than either of the components when it exhibits negative deviation from Raoult's law.