Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: MrHappy0 on April 23, 2012, 06:31:53 PM
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So I was reading a problem that asked why acetone was effective in cleaning wet glassware? This is from a Thermo book but I remember coming across the same question in Organic chem lab and couldn't answer it back and still can't. The book says it forms a low-boiling azeotrope with water but wikipedia disagrees and says there is no azeotrope. If I ignore that I still am confused how this would make cleaning wet glassware more effective.
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Basically, it dissolves water and is much more volatile than water. You rinse all the water off with acetone, and the acetone evaporates rapidly, leaving dry glassware.
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how does the azeotrope play in, though?
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There is no azeotrope of acetone and water. The phase diagram is here: http://www.see.ed.ac.uk/~jwp/procalcs/procalcs/mixtures/nonideal/slides/data/acetone-w.jpg (http://www.see.ed.ac.uk/~jwp/procalcs/procalcs/mixtures/nonideal/slides/data/acetone-w.jpg)
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Yeah, wikipedia says this also but My Pchem book has a question that says there is and I was asked the same question in an organic chem lab. How is this possible?
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What exactly was the question? The question as you wrote it in your original post does not imply the existence of an azeotrope, and you don't need to invoke one to answer the question.
If the book insists that there is a low-boiling azeotrope of acetone and water, what would that imply about the volatility of a mixture of acetone and water? How would the boiling point of droplets of the azeotrope on the glassware compare to the boiling point of droplets of water on the glassware?