another question..sugar and salt solubility

they both dissolve pretty fast. On the basis of electromagnetism, I would expect a polar solute to dissolve faster than a nonpolar solute because the polar atoms would have an attractive force to the water molecules.

but , how come that sugar dissolves in water ?.Water is polar and sugar isn't.The rule says , " a like dissolves a like ".

Sugar IS polar in the same way as water is.

first of all...I never was very good at chemistry and I took it a long time ago.

sugar is H2CO. C has 4 valence, H's have 1 valance electron, and O has 6 valence electrons. due to the octet rule they want 8 or 0 for stability. the only configuration that appears to work this way is, I think, the following:

H
|
C=O
|
H

the oxygen would have 2 more pairs of electrons on it. since electrons are negatively charged, that means the oxygen would have a net negative charge. the hydrogens only had 1 electron but it is being shared in a single bond with carbon, so their proton is exposed which is positive. so it looks to me that sugars are polar also.

A sugar contains multiple -OH groups that are capable of hydrogen-bonding (regions of local polarity, even though the molecule may not have a net polarity). That's why it's soluble.

Common sugar, sucrose, is C12H22O11 and has the following structure:


As patiodog says, there are several polar OH groups, not to mention the unbonded electrons on the other 3 oxygens.