Interchangeable joint kit

[MHourigan]

Hi all
I am stuck with trying to put together a condensation kit using the quick- fit-kits. Haven't done one for ages and it is for a prac teacher, for session 1 Monday morning.
Maureen

[MHourigan]

Hi its me again
This teacher is using 50/50 ethanol/water mix to fill conical flask in kit?? Also asking for conical flask x 2 for collection of condensed materials. If this helps anyone who knows what he is talking about as it is Friday and I am not with it at all today
Thanks people
Maureen

[dime]

The flasks in our kits is a pear shaped flask and holds 50 mls, but you wouldn't fill 'em up. Thats what he puts the ethanol and water mix in. I imagine he would only want a small flask to collect the distilled ethanol, actually a beaker would do or anything really.
It's a bit hard to describe how to set up the condensor etc., but his supervising teacher could show him if he can't do it himself

[lada]

We too, use the pear shape flasks for students. Then water bath to immerse it in. But for demo I use a larger round bottom flask and heat it on a heating mantle.
Put some boiling chips in flask and attach a T-shaped goose neck joint. On the top end attach thermometer , on the horizontal end attach condensor. The water for cooling enters condensor at lower end and exits at upper end. The distilled alcohol can be collected in a clean small beaker or any other suitable vessel.

Well, does it make sense??
Lada

[MHourigan]

Thanks guys
The young prac teacher has just put it together for me I am now just copying it down for the record! cannot wait to see it work. He is separating the ethanol from the water, using different boiling temps!! It does have a name but it is friday and went in one ear and out the other!
Thanks Maureen

[lada]

Hi, it is called fractional distillation and it is just as you said, separating liquids with different boiling points.
Ahh, the joy of science.
have a nice weekend.
lada

[MHourigan]

Thanks Lada for that! Science is cool, love it!
Maureen

[labbassistant]

Morning,

I have a teacher wanting to distill 50% ethanol and water but need to heat it at 80 degrees so the water doesn't boil.
Is there a way to put a thermometer in the quick fit set up to monitor this?
Thanks!

[bigmack]

There should be a bung with probably a silicone rubber grommet in it that takes a Thermometer. It fits in the top of the Tee

quickfit.jpg

quickfit therometer.jpg

Sometimes they are made of Teflon .

quickfit caps.jpg

Your teacher is in for a big supprise .
Yes Ethanol boils at 83 degC and water boils at 100 degC , But when you mix them together , the mixture will boil at a temperature that is a between 83 -100 degC and is proportional to how much water verses Ethanol is in the mix .

They will try all they like to hold the temp at 80(83) deg to try and seperate the Ethanol ,but it can't be done .If they do manage to hold it at 80 then it will not be boiling , and if its not boiling nothing will come off .

This a dodgy concept that has every teacher confused . They will have to turn up the heat ( not the temperature) to get the mixture to start boiling . At this point , vapour will leave the boiling flask , but it will not be pure alcohol . It will be a mix of the water and alcohol . It will contain more alcohol than water initially however. But the longer they run , the less alcohol will be in the mix and the more water will come off with it .

Now if they were to make a tall reflux column , yes , the alcohol will fraction to the top of the reflux tower and be close to pure Ethanol at 83 deg and will be able to be measured at the top , but interestingly , down at the boiling flask , the temp will be somewhere between 83 and 100degC .

Using a reflux still is the only way to separate alcohol from water .

[labbassistant]

Found them, thank you.

Ohhh interesting! I'll have to remember that for next time.

Thanks again!

[bigmack]

No worries

[mtg]

Interested to know if people are still doing this prac. We do distillation in year 7 with quickfit. Don't think we do and fractional distillation anymore.

[Labbie]

Bigmack as always thank you so much for all that wonderful information. Well done. You have a gift

[bigmack]

Bigmack as always thank you so much for all that wonderful information. Well done. You have a gift

Thanks Labbie .....how ever I woke up in the middle of the night and realized I had the Boiling Temp of Ethanol wrong
Its 78.3 degC not 83 as I had posted and as such ,the mixture will boil anywhere from 78.3 to 100 deg depending on ratio .

Sorry this is a bit off topic , but for those interested , there is a very useful graph that can be used to show what the boiling point of a mixture of Water and Ethanol is and what the Alcohol by Volume will be after distillation .

So if the mixture is 50:50 , we start at 50% ABV on the bottom line , go up to the blue line .At this point we can see that the boiling temp is just under 83 deg .We now draw a line horizontal to the red curve and project down . This will show us that after a single distillation , the collected Condensate will be 80% ABV

50% Ethanol water curve.png

If we keep distilling , the proportion of ethanol left in the boiler will get less and less.
At 10% ABV in the boiler , we can now see that the boiling point has risen to around 93 degC and the distillate has dropped to around 53%ABV

10% Ethanol water curve.png

[labbassistant]

Thanks for your help. We tried the reflux column like you suggested and the teacher said it worked well (these photos are after the prac)
They ended up getting more distilled with the reflux column, (they had the original set up for comparison)

[bigmack]

Glad it was helpful

Gosh your teacher is brave using a Bunsen under that setup .
I'm pretty sure that it's somewhere in CSIS that you should only use an electric heating Mantle in case of the flask cracking and an alcohol fire .

I could well be wrong about that though.

[Anna Z]

Interested to know if people are still doing this prac. We do distillation in year 7 with quickfit. Don't think we do and fractional distillation anymore.

Distillation will feature next year in Senior Chem, study change happening