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Hydrogen Bond
The highly electronegative or electron-hungry oxygen atom in methanol sucks electron density away from the hydrogen atom bonded to it. Denuded of electrons, the hydrogen atom is left with a partial positive charge -- not a full positive charge, however, because it still retains some electron density. The oxygen atom, by contrast, becomes electron-rich and therefore is left with a partial negative charge. Thanks to the partial charges, the hydrogen atom on one molecule of methanol now experiences an attraction towards the oxygen atom on another methanol molecule, so they interact to form a weak hydrogen bond.
Solubility
Water is another liquid that can form hydrogen bonds, and the similarities between the two ensure that methanol is highly soluble in water. Like water, methanol is also reasonably good at dissolving a variety of salts, although its qualities in this regard are inferior to those of water. Thanks to the carbon and its attached hydrogens, methanol is slightly less polar than water, meaning the charge distribution over the molecule as a whole is somewhat less uneven.
Structure
The molecules in pure methanol adopt a cyclic tetrahedral arrangement with four methanol molecules forming a ring; each molecule is hydrogen-bonded to its two neighbors. This is not a static structure, however, because the molecules are moving. At room temperature, the molecules in methanol have enough energy to break the hydrogen bonds and later reform new ones, so the overall arrangement of the molecules in the liquid is continually changing.
Acidity
The acidity of methanol is roughly the same as that of water. Chemists often talk about acidity in terms of the pKa, a number that measures the tendency of a molecule to donate or give away a hydrogen ion. Lower pKa numbers are more acidic. Water has a pKa of 15.7, while methanol has a pKa of 15.5. By way of comparison, acetic acid (vinegar) has a pKa of 4.79, while nitric acid has a pKa of -1.4.