artemov
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Questions on Eutectics
Specifically, acetic acid/water eutectic.
The graph below is from this paper : https://www.tandfonline.com/doi/abs/10.1080/01496395.2012.71...
Red and blue text/lines are added by me.
Vinegar is said to have a freezing point of around -2C (Google).
I supposed the freezing point of an eutectic mixture is defined as the temperature where solids start to appear?
If I keep the mixture just slightly below its freezing point, say -2.5C, I would not expect the whole thing to freeze solid no matter how long right?
It would be just a bit of ice and a very very slightly concentrated vinegar?
My fridge is about -15C. At this temp should I expect a lot more ice and a liquid mixture of about 42% acetic acid?
This YouTube video seems to show a complete freeze https://www.youtube.com/watch?v=q8yedBBScos
I thought eutectic mixture dun completely freeze until the eutectic temp, which is about -27C here?
Cheers. I am conducting an experiment in my fridge now 
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macckone
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Eutectics do not melt or freeze cleanly.
At the eutectic point they will freeze cleanly.
Freeze purification is an art, not a science and the product appears far from pure.
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DraconicAcid
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Quote: Originally posted by artemov  |
If I keep the mixture just slightly below its freezing point, say -2.5C, I would not expect the whole thing to freeze solid no matter how long right?
It would be just a bit of ice and a very very slightly concentrated vinegar? |
That's correct, but what you'll often find is a very slushy ice that will be very difficult to separate from the rest of the mixture.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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artemov
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Ok thanks guy.
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