like dissolves like?chem 問題

bascially like dissovles like is true

methylbenzene is only sparingly soluble in water

methylbezene has weak van der waal's forces
water has hydrogen bonding

water consists of 1 oxygen atom and 2 hydrogen atom
oxygen is more electronegative than hydrogen,
therefore oxygen will draw electron to itself in a covalent bonding
such that the electron density in water molecule is not balance
between oxygen and hydrogen

since the electron density is not balance,
therefore a little positive(delta positive) on hydrogen
and little negative (delta negative) on oxygen
therefore water molecule is polar

methybenzene composed of carbon and hydrogen,
they have similiar electronegativity ,
the electron density is quite balance over the covalent bond,
therefore methylbenzene is not a polar molecule

2009-01-23 23:38:36 補充：
should read "van der waal force"