#4 - Creating Ethanol from alcohol
Distillation set-up.
Ethanol is a rather useful substance to have around the lab, but it seems to be getting difficult (and expensive) to obtain in the UK; so I decided to make my own.
Plain Vodka contains around 37.5% Ethanol per volume of liquid and that’s what I used for this process. Luckily for me, our drinks cabinet contained a very old bottle that had around 200ml left so this was an ideal starting point. I also noticed that the top was very loose.
To start, I initially made some weight measurements and brief calculations.
Weight of empty 10ml graduated cylinder - 22.40g
Weight with 10ml distilled water - 32.19g
Weight with 10ml Vodka - 31.80g
Since the majority of the Vodka is actually water, we can subtract the weight 10mL of water, from the weight of 10ml of Vodka and obtain the weight of the Vodka Ethanol (less any other ingredients).
So this means that 10mL of my Vodka Ethanol weighs: (32.19g – 31.80g) = 0.39g 10mL or 0.039g / mL
The density of 100% Ethanol is: 0.789 g/mL
So: 0.789g / 0.039g = 20.23%
Now this is just under half what I was expecting (or written on the bottle label) but two things spring to mind.
Firstly, the Vodka was rather old (I estimate over 12 years) and the screw cap was very lose. It also gets rather warm in the cabinet where it’s stored so it’s possible that a percentage of the Ethanol has evaporated. Also, there was only around 200ml of Vodka left in the bottle and when I performed the
initial weight measurements; perhaps I should have shaken the contents first to make sure they were fully mixed.
The next task was to perform the actual distillation process.
Ethanol has a boiling temperature of 78oC and water 100oC. However, as a combined solution the boiling point is actually lower.
A simple distillation setup was assembled and 200ml of Vodka placed in the conical flask and slowly heated. Don't forget to add a couple of boiling chips to the flask to help prevent bumping. I should stress here that I use an electric heater for boiling flask and not a traditional Bunsen or spirit burner. Ethanol fumes are explosive and having a naked flame around is not a good idea !!
A carful watch was kept on the temperature to make sure that the water content didn’t get a chance to start to boil; we are only after the Ethanol content but as the distillation process continued, the temperature started to rise in the flask, and it became necessary to keep turning down the heat.
After around 30 minutes, I switched off the heat and allowed the process to slow down and stop.
10 mL of the collected distilate (Ethanol hopefully) was then weighed, giving a weight of 8.53g or 0.853g /mL
Calculating the percentage of Ethanol recovered is performed like this:
Density of Ethanol / weight per mL recovered... 0.789 / 0.853 = 92.5%
I would have been happy with anything around the %70 region, but the purer the better.
The Ethanol was then transfered to a labeled glass bottle for later use in the lab.
Plain Vodka contains around 37.5% Ethanol per volume of liquid and that’s what I used for this process. Luckily for me, our drinks cabinet contained a very old bottle that had around 200ml left so this was an ideal starting point. I also noticed that the top was very loose.
To start, I initially made some weight measurements and brief calculations.
Weight of empty 10ml graduated cylinder - 22.40g
Weight with 10ml distilled water - 32.19g
Weight with 10ml Vodka - 31.80g
Since the majority of the Vodka is actually water, we can subtract the weight 10mL of water, from the weight of 10ml of Vodka and obtain the weight of the Vodka Ethanol (less any other ingredients).
So this means that 10mL of my Vodka Ethanol weighs: (32.19g – 31.80g) = 0.39g 10mL or 0.039g / mL
The density of 100% Ethanol is: 0.789 g/mL
So: 0.789g / 0.039g = 20.23%
Now this is just under half what I was expecting (or written on the bottle label) but two things spring to mind.
Firstly, the Vodka was rather old (I estimate over 12 years) and the screw cap was very lose. It also gets rather warm in the cabinet where it’s stored so it’s possible that a percentage of the Ethanol has evaporated. Also, there was only around 200ml of Vodka left in the bottle and when I performed the
initial weight measurements; perhaps I should have shaken the contents first to make sure they were fully mixed.
The next task was to perform the actual distillation process.
Ethanol has a boiling temperature of 78oC and water 100oC. However, as a combined solution the boiling point is actually lower.
A simple distillation setup was assembled and 200ml of Vodka placed in the conical flask and slowly heated. Don't forget to add a couple of boiling chips to the flask to help prevent bumping. I should stress here that I use an electric heater for boiling flask and not a traditional Bunsen or spirit burner. Ethanol fumes are explosive and having a naked flame around is not a good idea !!
A carful watch was kept on the temperature to make sure that the water content didn’t get a chance to start to boil; we are only after the Ethanol content but as the distillation process continued, the temperature started to rise in the flask, and it became necessary to keep turning down the heat.
After around 30 minutes, I switched off the heat and allowed the process to slow down and stop.
10 mL of the collected distilate (Ethanol hopefully) was then weighed, giving a weight of 8.53g or 0.853g /mL
Calculating the percentage of Ethanol recovered is performed like this:
Density of Ethanol / weight per mL recovered... 0.789 / 0.853 = 92.5%
I would have been happy with anything around the %70 region, but the purer the better.
The Ethanol was then transfered to a labeled glass bottle for later use in the lab.
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