Q: Do we need to use a trap?

A: No. We are evaporating directly into the house vacuum, which is internally trapped.

Q: Why do we need to apply heat when evaporating methylene chloride?

A: Even though methylene chloride (aka. "dichloromethane') boils at a low temperature, and therefore has a high vapor pressure, it becomes cold during evaporation. Unless we offset this by keeping the solution near room temperature, it will take a long time to remove the (cold) solvent because the cold solvent has a much lower vapor pressure.

©2001,2002 Daniel A. Straus