Correlation Between Intermolecular forces and solubilityand solubility

Intermolecular forces and solubilityand solubility

Why mixWhy mixtures mix•Consider a glass of wine. Why do alcohol, water, & pigment mix together?•There must be attractive forces.Intramolecular forces occur between atomsIntermolecular forces occur between molecules•The factors that determine solubility are the strength of IMFsand speed of molecules.•4 types of intermolecular forces: ionic, dipole-dipole, hydrogen bonding, and London forces.

Electronegativity & IMFsIMFs•?ENessentially defines the type of IMF.•Ionic bonds form if the ?ENis 1.7 or greater.•Dipole-dipole (polar covalent) is around 0.5-1.7.•Hydrogen bonding is a type of dipole-dipole.•London forces exist in all molecules, but are especially important in non-polar covalent molecules (where ?ENis less than 0.5).•Recall that ionic are strongest.•Dipole-dipole are not as strong.•Hydrogen bonds are about five times stronger than a regular dipole-dipole bonds.•London forces are weakest .

Hydrogen bondingHydrogen bonding•H-bonding is a special type of dipole-dipole attraction that is very strong.•It occurs when N, O, or F are bonded to H.Q-Calculate the ?EN for HCl and H2O•The high ?EN of NH, OH, and HF bonds cause these to be strong forces.•Also, because of the small size of hydrogen, it’s positive charge can get very close to the negative dipole of another molecule.•It is so strongly positive that it will sometimes exert a pull on a “lone pair”in a non-polar compound .