Question

Why do we wrap with a wet paper towel in distillation?

1) To prevent the sample from drying out
2) To increase the rate of distillation
3) To improve the separation of components
4) To reduce the risk of contamination

Answer 1

We wrap a wet paper towel around a distillation apparatus to increase the rate of distillation through evaporative cooling, which is more effective than other options listed such as preventing drying out, improving separation, or reducing contamination. Option 2 is correct.

Step-by-step explanation:

The reason we wrap a distillation apparatus with a wet paper towel is to increase the rate of distillation. During a distillation process, heat is applied to a liquid mixture to vaporize the component with the lower boiling point. To maintain an efficient distillation, the vapors must be condensed back into a liquid. Wrapping the distillation apparatus with a wet paper towel aids in cooling the glassware, particularly the condenser, by utilizing the evaporative cooling effect.

As the water in the towel evaporates, it absorbs heat from the glassware, thus enhancing the condensation of vapor and increasing the distillation rate. This practice does not prevent the sample from drying out, improve separation of components, or reduce the risk of contamination; instead, these are mitigated by proper setup and operation of the distillation apparatus.

Additionally, capillary action, the phenomenon where liquid flows within a porous material, as in the case of wine wicking up a paper towel, is not the primary reason for the use of a wet paper towel in distillation. Rather, the wet paper towel serves as a tool for cooling.