Fractions of distillation .

  • Thread starter Cheman
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Fractions of distillation.....

Some of the fractions which result from fractional distillation seem to share carbons of the same length - yet these form different fractions. Why?

Eg - Petrol is carbon chain length 4 - 12, naptha is 7 - 14 and kerosine is 11 -15; why the overlap when they boil at very distinct temps. ie - petrol 40 - 100, naptha is 100 - 150 and kerosine is 150 - 250 degrees C.

Thanks. :smile:
 

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  • #2
Borek
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Cheman said:
Some of the fractions which result from fractional distillation seem to share carbons of the same length - yet these form different fractions. Why?

Eg - Petrol is carbon chain length 4 - 12, naptha is 7 - 14 and kerosine is 11 -15; why the overlap when they boil at very distinct temps. ie - petrol 40 - 100, naptha is 100 - 150 and kerosine is 150 - 250 degrees C.

The simplest answer will be that boiling point depends not only on number of carbons, but also on the chain structure - whether it is straight or branched.


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  • #3
Bystander
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"Distillation" --- evaporation of a MIXTURE. Do a few calculations of liquid and vapor compositions that are at equilibrium at the temperatures bounding the fractions you've listed.
 

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