What is done with glass wool to control bumping in vacuum distillation?

In vacuum distillation, bumping refers to the sudden, uncontrolled boiling of a liquid that can occur when vapor pressure is much lower than atmospheric pressure, leading to rapid vaporization and the potential for the liquid to be expelled. Glass wool plays a crucial role in mitigating this effect.

When glass wool is introduced into the distillation flask, it creates a surface area for the vapor to condense upon as it rises through the flask. This added surface area allows for more controlled vaporization and provides sites for nucleation, which helps to stabilize the boiling process. By filling space above the liquid, the glass wool effectively reduces the chances of liquid vigorously bumping up into the distillation head or condenser.

The other options do not address the purpose of glass wool in vacuum distillation effectively. Lowering the liquid temperature or soaking glass wool in the distillate would not contribute to controlling bumping. Placing it at the bottom of the flask can impede liquid flow but does not provide the same vaporization control as strategically placing it to create areas that enhance stability during boiling. Thus, the introduction of glass wool to fill space above the liquid is the most effective method for controlling bumping in this experimental setup.