Polar covalent molecules may dissolve in polar solvents. Not all polar covalent molecules will be soluble in polar solvents.Non-polar covalent molecules will form intermolecular forces with the molecules of non-polar solvents. The energy released may be enough to break the intermolecular forces between the non-polar covalent molecules so non-polar covalent molecules tend to be soluble in non-polar solvents.Non-polar simple covalent molecules tend to be insoluble in polar solvents. This is because the intermolecular forces in the polar solvents are too strong to be broken by the energy released by their interaction with the non-polar molecules.Some organic molecules have hydrophilic and hydrophobic parts. Short-chain alcohols are miscible with water because the Hydroxyl (-OH) group can form hydrogen bonds with the water molecules. As the chain length increases, the alcohols become less miscible as the London forces become more significant and the hydrogen bonding becomes less significant.