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Lab 1: Distillation (Exp. 3105-1)

Nate Hall (w/Kevin Ge!!a)" #$e% 3105

&.'.: ei a

*!pose: To attempt to completely distill methanol from a 50-50 methanol-water mixture using

both the simple and fractional distillation techniques. Distilling utilizes the difference in boilingpoints between water and methanol to boil out all of the methanol, which is then condensed

again.

*$+si,al *!ope!ties &able (t$e!e is no !ea,tion $e!e):

#o%pon (/%ol) '%ont bp(#)

ethanol !"#$%#& $'.05 '0.0 m( )5

*ater !#'%& +.0' '0.0 m( +00

aet+:

ethanol !flammable, toxic, carcinogen&

- toxic if inhaled, touching sin, or ingested

- ery flammable

- can cause irreersible effects

- wear goggles and gloes

*!o,e!e:

+. /et up one of the following apparati. or simple distillation1

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2otes1 use a +00 m( round-bottomed flas for the distilling flas, and a a 50 or +00m(

graduated cylinder for the receiing flas

or fractional distillation1

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'. "lamp the apparatus securely, but do not strain the glass, and set up the distilling flas on a hot

plate for heating.$. 3dd 40 m( of the sample solution to the distilling flas.4. 3dd a boiling chip and heat until the solution boils to a rate of roughly three drops per second

into the graduated cylinder. !D% 2%T put the plate on high heat&5. 3t eery ' m( of methanol distilled, hae one person record the temperature at that particular

olume, until the temperature tops off at somewhere around +00"). 3t the aboe temperature mar, stop the distillation, so the flas is not boiled to dryness6. "lean up, wash hands, etc.. 7raph the results as Temp !"& s. 8olume of Distillate !m(& !y s. x&, showing both the

fractional and simple result cures

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Data &ables/G!ap$:

2!a,tionalDistillation

ethanolDistilled !m(&

Temperature!"&

Fractional

' )54 )6) 60 6'.5

+0 6$+' 65+4 6)+) 6+ '

'0 '' 99

i%pleDistillationethanolDistilled !m(&

Temperature!"&

' 604 65

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) 6 0

+0 ++' $+4 5+) 9

+ 9$'0 94'' 95'4 9)

#on,lsion:The simple distillation that was attempted was relatiely successful. The distillation

should hae produced a somewhat impure distillate, since the boiling points for water and

methanol are $5" apart !simple distillation wors best when the boiling points of the

substances are further apart, a difference of $0-40 is a minimum&. This was true, as the

distillate collected exceeded '0 m( !half the original solution& before the temperature reached

+00", which means that some water must hae also boiled off into the apor to mae up theextra 4 m( or so, resulting in a slight impurity. The fractional distillation had a higher success

rate, which maes sense considering its higher efficiency with substances that hae less

difference in boiling point. 3dding the fractioning column howeer also results in a longer time

taen to distill the methanol out, as shown by the slower increase in temperature on the graph.The fact that neither distillation reached +00" can be explained by not haing the

thermometer bulb low enough during the experiment. :f the bulb is not low enough, the

temperatures that are being measured are those of apor haing more time to condense and

lower in temperature. This effect could also account for the temperatures being a little lower

than expected at the '0 m( mar.

*ost-Lab estions:+. a& #igher atmospheric pressure results in a higher boiling point. ;oiling occurs when

apor pressure of a liquid equals atmospheric pressure. The higher atmospheric

pressure would require a higher apor pressure, which can be achieed by add more

heat, or reaching a higher boiling point.

b& 3n uncalibrated thermometer would read temperature at a shifted alue. /o +00"

might read as 95", or ++0". This would mae the boiling point of water seem lower or

higher, respectiely, to a iewer. #oweer, the true boiling point of the water would

remain the same.

c&

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$. a& 2ot adding boiling chips would mae the boiling solution much more chaotic and

turbulent, which might allow some of the unseparated solution to spew into the

condenser and then into the distillate container.

b& #eating the flas too quicly can result in a higher impurity of the distillate, since the

apor will moe faster through the system, and could carry some of the other substances

with it.