+
Related Flashcards
Related Topics
Cards In This Set
| Front | Back |
|
What is distillation?
|
Distillation is a process which involves heating a substance until it vaporizes, condensing the resulting vapours by cooling
|
|
What is distillation?
|
And then collecting the condensate (disttilate) in a separate vessel called a receiver
|
|
What is the difference between distillation and refluxing?
|
The only difference is that in refluxing the condensate is returned to the original vessel
|
|
When is the distillation technique useful for separating a mixture?
|
When the mixtures have different boiling points; distillation also is the principle method for purifying liquids
|
|
What are the 3 conditions that need to be met for distillation to occur?
|
1) At least one component in the mixture must be volatile
|
|
What are the 3 conditions that need to be met for distillation to occur?
|
2) If two or more volatile liquids are to be separated, then they must have a wide separation between their boiling points (50 or more)
|
|
What are the 3 conditions that need to be met for distillation to occur?
|
3) The components must not form an azeotrope
|
|
If the liquid is a pure substance, how will the boiling point be affected?
|
The boiling point measured will remain constant throughout the distillation
|
|
If the liquid is a mixture of two or more miscible substances then how would the boiling point be affected?
|
Boiling point will not be constant but will vary continuously during distillation
|
|
Boiling point will not be constant if liquid is a mixture of two or more miscible substances. Why?
|
Because composition of liquid being distilled also varies continuously during distillation;
|
|
Boiling point will not be constant if liquid is a mixture of two or more miscible substances. Why?
|
Since vapour pressure of liquid varies with composition, so does b.p
|
|
Sometimes a mixture of 2(+) liquids distills at constant temp with constant comp even through separately, components have different b.p, why?
|
This occurs when intermolecular interactions (H- bonding) take place between the components of the mixture. These are Azeotropes.
|
|
What is an example of an azeotrope?
|
Ethanol and water (will form an azeotropic mixture at 95% and 5% respectively
|
|
Be sure to understand phase diagram
|
Ok
|
|
How can we summarize a simple distillation of two liquids?
|
1) Observed boiling points are always between the boiling points of the pure components rising gradually as the distillation proceeds
|
