Water tends to dissolve only ionic substances. Why is ethanol a better solvent than water?
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Note first of all that water is called "the universal solvent". This is because it dissolves more substances than most other solvents. It will not however dissolve non-polar or purely covalent materials. Although water is a covalently bonded substance, the presence of oxygen in its unsymmetrical molecule makes it highly polar. The general rule for solubility is 'like dissolves like', meaning that to dissolve a substance one needs to choose a solvent that is similar in bonding to it. A polar substance is one in which one end of the molecule behaves as if it is charged relative to the other end. A polar material will dissolve ionic materials (actually composed of charged particles) because of the real and apparent charges the materials have. Ethanol on the other hand is more geometrically symmetrical and therefore is not nearly as polar as water. It therefore will more readily dissolve non-polar substances like oils than water would. Because it is slightly polar, ethanol will also somewhat dissolve polar substances.
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No water will also dissolve covalent substances. Methanol, ethanol, propanol, acteone, actealdehyde and countless other polar covalent compounds are very soluble in water. There is no such thing as a better solvent although water is probably more versatile than ethanol.
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Ethanol is not universal solvent