i am an AP smashville247.net student and also there is a tiny detail worrying polarity of molecule that i am confused about.

My review book (Princeton review) says that ethanol has stronger intermolecular forces than methanol since it has a huge molecular mass and is therefore much more polarizable and much more soluble in water 보다 methanol.

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Yet, my smashville247.net textbook says that both ethanol and methanol are miscible in water, however the an ext the carbon chain increases, the much less miscible the becomes. More supporting this explain is the truth that methanol is less soluble in hexane, a nonpolar substance, 보다 ethanol. Thus ethanol is less polar. Plus, heptanol is hardly dissolve in water, however according to the Princeton Review"s logic, it should be even much more soluble in water than methanol because it has a bigger molecular mass.

So, i m sorry is it? go the addition of CH3s make a molecule much more or less polar, and much more or much less miscible in water?


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inquiry Feb 22 "17 at 19:35
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JessJess
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If your publication says exactly that, then it claims nonsense. Sure enough, the addition of CH2"s provides a molecule less polar. Together for the solubility in water, methanol is miscible - i.e., infinitely well soluble in it. Therefore is ethanol. Just how would you to compare the two infinities?

That being said, the larger molecule that ethanol is indeed an ext polarizable (not an ext polar, mind you!), and also has more intermolecular interactions per molecule than methanol, which accounts because that the higher boiling point.


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answer Feb 22 "17 at 20:21
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Ivan NeretinIvan Neretin
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my review book (Princeton review) says that ethanol has actually stronger intermolecular pressures than methanol due to the fact that it has actually a big molecular mass and also is therefore more polarizable

True

Ethanol does ~ above a molecule by molecule basis have actually stronger intermolecular forces in between itself and water than methanol and also water.

and much more soluble in water than methanol.

See more: Does Methylphenidate S How Long Does Focalin Stay In Your System For Drug Test ?

False

Yet, mine smashville247.net textbook claims that both ethanol and also methanol room miscible in water, yet the more the carbon chain increases, the less miscible that becomes.

True

Why?

As you boost the number of carbon-chain linkages the polarizibility of the molecules does in reality increase.

However, the thing that makes little chain alcohols dissolve in water is not the reality that you deserve to induce a non-polar shortcut to have a brief lived regional dipole (van der Waals forces), but because of the permanent dipole the the alcohol group. The hydrogen ~ above a alcohol (or water) is really positive and the oxygen is very negative, so they tempt other polar groups roughly them in a reasonably well ordered manner. For short chain alcohols the alcohols in ~ the end of the chain deserve to take the ar of the oxygen and also hydrogen on various other water molecules and with the entropy inherent with mixing deserve to be miscible v water.

For long chain alcohols the non-polar chains deserve to be polarized, but they execute not interact with water nearly as strong as other waters and also the entropy inherent with mixing is not enough to counter the power difference. And also so if over there are any other waters "nearby" the water molecules will self-segregate, together water is much more attracted to various other waters than to the non-polar chains the they room inducing into developing dipoles.

As you add much more alkane linkages the molecule becomes less polar but more polarizible - however this go not add much (comparatively) to the solubility that a non-polar molecule in a really polar solvent like water contrasted to highly polar groups.