# simple & vacuum distillation

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#### inaccensa

##### Full Member
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There are 2 solvents that are being separated. I understand that the first solvent will not boil at its true temp, since it's vapor pressure has decreased. Does the second solvent boil at its true boiling temp? Lets say one boils at 30c and other at 100C. so the solvent A will may be boil at 35C, but will solvent B boil at 100c or higher, assuming that there are no other impurities.

#### pastryman

##### Full Member
i would think solvent B also boils at a higher temperature but i could be wrong.

#### ezsanche

##### Full Member
10+ Year Member
5+ Year Member
There are 2 solvents that are being separated. I understand that the first solvent will not boil at its true temp, since it's vapor pressure has decreased. Does the second solvent boil at its true boiling temp? Lets say one boils at 30c and other at 100C. so the solvent A will may be boil at 35C, but will solvent B boil at 100c or higher, assuming that there are no other impurities.
Assuming that if all of the solvent A is gone by 35 C. Then why will B boil higher than 100C if by the time the temp passes 35 it is the only solvent present?

#### pastryman

##### Full Member
Actually inaccensa, vacuum distillation does not lower the vapor pressure of the solvents. it only decreases the ambient pressure above the solvents so the VP gets higher than ambient pressure and the solvents boils faster. Solvents boil when their VP is higher than their ambient pressure and vacuum filtration lowers ambient pressure. So both solvents should have a lower BP than their normal BPs. And yes, ezsanche, your logic was better than mine but we were both wrong.