orgo lab 4

distiliation

boiling liquid and collecting the condensate into another vessel

reflux

boiling of the liquid with the return of the condensate to the original flask

why do you place the thermometer not touching the liquid

because it provides a more accurate reading

soluble nonvolatile in the water example

NaCl in water

insoluble nonvolatile impurity example

sand

simple distillation temp

to separate 2 liquids you need a 40-50C difference in BP

theoretical plate

changing through phases of evaporation/condensation

theoretical plate more

vapor gives off more lower boiling compound

flat regions in the graph means what

pure compounds are there

slope regions in the graph means what

mixture

BP branching

branched alkanes have lower BP than the corresponding unbranched constitutional isomers

BP cyclic compounds

have higher BP than straight chains

BP hydrogen bonding

this bonding raises BP

hydrogen bonding is with what elements

F, O, N

For simple distillation, can you account for the boiling point of your products? In terms of the known boiling points for the pure components in your mixture?

yes because of their difference in boiling points. The compound with the lower boiling point will distill first and then increase towards the other compounds higher boiling point.

from the plot of the boiling point vs the volume of distillate in simple distillation, what can you conclude about the purity of your product

the product of both cyclohexane and toluene was not fully pure because the graph showed the temperature gradually increasing with every drop of condensate collected

effect of boiling point in a solution by soluble nonvolatile substance

raising the BP due to the impurities

what is the effect of an insoluble substance such as sand or charcoal

will have no effect on the BP

what is the temperature of the vapor above the boiling solutions in part a and b

both boiling solutions would be vapors boiling point,100 C

why is it extremely dangerous to attempt to carry out a distillation in a completely closed apparatus

a closed apparatus causes pressure to build up as the products evaporate and vapor forms. This pressure eventually explodes the apparatus

why is better separation of two liquids achieved by slow rather than fast distiliation

you must achieve equilibrium between ascending vapor and condensation to purify, but if you have fast distillation you will not achieve this equilibrium

alcohol boiling point

have hydrogen bonds, so their BP is higher than compounds without hydrogen bonds

amines metling point

have hydrogen bonds, but their hydrogen bonds aren’t as strong as the ones in alcohols because O is more electronegative than N

carboxylic acids boiling point

have the highest BP

alkanes boiling point

lowest boiling point