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Topic: Distillation of Ethanol Water mixture 50/50  (Read 12883 times)

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MarkNY8679

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Distillation of Ethanol Water mixture 50/50
« on: October 19, 2005, 07:45:14 PM »
I am having a lot of difficulty understanding and visualizing distillation. I need help with the following questions and feel I am way off.

1) Why is it dangerous to attempt to carry out a distillation in a completely closed apparatus (one with no vent to the atmosphere) wouldn't this result in the flask exploding as the vapors trying to escape would build increasingly in pressure?

2)Why is a packed fractionaating column more effecient- i think this has do do with increased surface arae but how does that relate to efficinecy?

3)In fractional distillation, liquid can be seen running  from the bottom of the distillation column back into the flask- what effect does this return condensation have on the fractional distillation- I have no clue

4)When water-cooled condensers are used for distillation, the water enertes the condenser at the lowest point and leaves at the highest. Why?- Is this so the water does not enter the collecting flask?

5)In simple distillation, can you account for the boiling point of your product in terms of the known boiling points of the pure compound of your mixture? - i think the answer is no

6)In the distiilation of a pure substance (ie water) why doesn't all the water vaporize at once when the boiling point is reached?

Offline mike

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Re:Distillation of Ethanol Water mixture 50/50
« Reply #1 on: October 19, 2005, 08:13:25 PM »
Quote
1) Why is it dangerous to attempt to carry out a distillation in a completely closed apparatus (one with no vent to the atmosphere) wouldn't this result in the flask exploding as the vapors trying to escape would build increasingly in pressure?
Correct.


Quote
2)Why is a packed fractionaating column more effecient- i think this has do do with increased surface arae but how does that relate to efficinecy?
Yes it does increase the surface area, don't know off the top of my head how this increases efficiency. I guess it results in better separation of vapour.

Quote
3)In fractional distillation, liquid can be seen running  from the bottom of the distillation column back into the flask- what effect does this return condensation have on the fractional distillation- I have no clue
Presumably more of one component will run back into the flask each time so you will gradually remove one component from the flask over time, while the other component stays in the flask.

Quote
4)When water-cooled condensers are used for distillation, the water enertes the condenser at the lowest point and leaves at the highest. Why?- Is this so the water does not enter the collecting flask?
Usually so you alsways have the coolest water in the condensor all of the time, if it is the other way then there will always be some slightly warmer water present in the condensor. Interestingly I knew a guy once who used to do it the other way around because he said the "in through the bottom, out through the top" method put unnecessary pressure on the hoses (what do people think?)

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5)In simple distillation, can you account for the boiling point of your product in terms of the known boiling points of the pure compound of your mixture? - i think the answer is no
I don't really know wht this means, I would have thought your product should be the same as the bp of the pure compound, or close to it.

Quote
6)In the distiilation of a pure substance (ie water) why doesn't all the water vaporize at once when the boiling point is reached?
not enough energy present for this.

Also I think that water ethanol is a non-ideal mixture for distillation.
There is no science without fancy, and no art without facts.

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