What is the purpose of trays in a distillation column?

• A. To Hold a Liquid Level and Allow Lighters to Vaporize
• B. To Provide Structural Support Only
• C. To Cool the Vapor Above the Tray
• D. To Mix the Incoming Liquid

Answer: (A)

Trays in a distillation column create the contact points where vapor and liquid interact. Each tray holds a thin layer of liquid, forming a surface on which the rising vapor can meet the liquid. The more volatile components in that liquid preferentially vaporize and join the vapor rising to the next tray, while the heavier, less volatile components stay with the liquid that flows downward. This vapor–liquid exchange happens on many trays, creating multiple equilibrium stages that drive the separation as you move up the column.

So the trays’ main function is to hold the liquid level and enable lighter components to vaporize into the rising stream, rather than merely providing structural support or cooling the vapor. Cooling is handled by a condenser at the top, and mixing occurs as a natural result of the contact, not as the primary purpose.