Development of the Modern Freezer. Bacteria are usually the cause of food decay, but they can't grow as well or at all in freezing temperatures, which are at 32 degrees Fahrenheit (0 degrees Celsius) or lower.
HF- polar molecule: dipole-dipole forces. There are also dispersion forces and H bond between HF. BF3- nonpolar: dispersion forces. Ar- Dispersion forces between Ar atoms.
(A) Fluorine is a more electronegative element than chlorine, so the single covalent bond in HF is more polar than the corresponding bond in HCl. Since the dipole moment of HF is therefore greater, dipole-dipole interactions between HF molecules are greater than they are in HCl. (B) Because of fluorine's high electronegativity, the hydrogen atom is almost completely stripped of electrons.