Question

A flask contains a mixture of isohexane and 3-methylpentane. One of the liquids boils at ${63}^{\circ }$C while the other boils at ${60}^{\circ }$C. What is the best way to separate the two liquids and which one will be distilled out first?

• A. Fractional distillation, isohexane
• B. b. Simple distillation, 3-methylpentane
• C. Fractional distillation, 3-methylpentane
• D. Simple distillation, isohexane

Answer 1

The correct option is A Fractional distillation, isohexane

When the difference between the boiling point of the two liquids is less than around ${40}^{\circ }$ C, fractional distillation is more efficient. The difference between the boiling points of isohexane and 3-methylpentane is only 3 degrees. So, fractional distillation is the best suitable method. Since, isohexane has a lower boiling point, it comes out first.