In a fractionating column used for distillation, what is the primary purpose of the trays or packing material?

• A. To provide insulation and prevent heat loss from the column
• B. To increase the surface area for vapor-liquid contact and improve separation efficiency
• C. To introduce air bubbles for the floatation process
• D. To collect the condensed liquid at the bottom of the column

Answer: (B)

Verified step by step guidance

1. Understand the role of a fractionating column in distillation: it is used to separate components of a mixture based on differences in their boiling points.
2. Recognize that trays or packing material inside the column serve to enhance the interaction between rising vapor and descending liquid.
3. Know that increasing the surface area for vapor-liquid contact allows for more efficient mass transfer, which improves the separation of components.
4. Identify that trays or packing do not primarily serve as insulation, air bubble introducers, or liquid collectors; their main function is related to vapor-liquid interaction.
5. Conclude that the primary purpose of trays or packing material is to increase the surface area for vapor-liquid contact and thereby improve the separation efficiency of the distillation process.