ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: breadkay on May 21, 2012, 08:21:09 pm
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Hi,
Through my research I have found that esters are polar and when they have a short hydrocarbon chain are soluble in water. So, how come an ester like ethyl ethanoate is seen to be insoluble?
Any help is appreciated, as always :)
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The lack of a Hydroxyl Group (OH) during when it condenses from ethanol and acetic acid therefore makes ethyl ethanoate insoluble. Because it doesn't have any OH groups, it cannot form a water molecule which makes it insoluble although there is a percentage of 3-8% solubility.
http://cavemanchemistry.com/cavebook/chsoap2.html
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Ok.
So it still is soluble, just not to a great extent?
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Yeah it's solubility is very low
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Awesome, cheers :) :)
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Sorry, got another question, haha :P
How come esters are slightly soluble then? Is it because of the highly electronegative Oxygen in the C=O bond that allows it to Hydrogen bond to some extent?
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Yes, that's what my teacher said :)
As always, the smaller it is, the more soluble it is as the polar functional group exerts a bigger influence on the overall polarity and hence it better dissolves in H2O (polar)
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Sorry, got another question, haha :P
How come esters are slightly soluble then? Is it because of the highly electronegative Oxygen in the C=O bond that allows it to Hydrogen bond to some extent?
Unfortunately I am not too sure with myself but I believe it is because the hydrogen bond with C=O is weak therefore it is soluble. It is not just the C=O that can have a Hydrogen bond with water as alcohol (OH) has a weak hydrogen bond with water which makes it soluble.
http://www.chemguide.co.uk/organicprops/esters/background.html