Two volatile and miscible liquids can be separated by fractional distillations into pure components under the condition

Options

A. They have low boiling points
B. The difference in boiling point is large
C. The boiling of two liquids are close to each other
D. They do not form axeotropic mixture

Answer

To solve the question regarding the conditions under which two volatile and miscible liquids can be separated by fractional distillation into pure components, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Volatile and Miscible Liquids**:
- Volatile liquids are those that evaporate easily at room temperature. Examples include ethanol and acetone.
- Miscible liquids are those that can mix together in any proportion without separating into two phases. An example is ethanol and water.

2. **Fractional Distillation Principle**:
- Fractional distillation is a technique used to separate mixtures of liquids based on differences in their boiling points.
- The process involves heating the mixture to form vapors, which are then condensed back into liquid form.

3. **Conditions for Fractional Distillation**:
- For effective separation using fractional distillation, the difference in boiling points of the two liquids must be relatively small.
- A common guideline is that the boiling point difference should be less than 10 Kelvin for efficient separation.

4. **Process of Fractional Distillation**:
- When the mixture is heated, the more volatile liquid (with a lower boiling point) will vaporize first.
- The vapor travels up the fractionating column, where it may condense and re-vaporize multiple times, enriching the vapor in the more volatile component.
- Eventually, the vapor that reaches the top of the column consists mainly of the more volatile liquid, which can then be collected as a pure component.

5. **Example of Suitable Liquids**:
- An example of two miscible liquids that can be separated by fractional distillation is acetone (boiling point 329 K) and methyl alcohol (boiling point 338 K). The difference in their boiling points is 9 K, which is suitable for fractional distillation.

### Conclusion:
Two volatile and miscible liquids can be effectively separated by fractional distillation when the difference in their boiling points is low, typically less than 10 Kelvin.