As a chemist, I can explain the differences in the dipole moments of water H2O and sulfur hexafluoride SF6 molecules.First, let's understand the dipole moment. A dipole moment is a measure of the separation of positive and negative charges in a molecule. It is a vector quantity and depends on the magnitude of the charges and the distance between them. Molecules with a non-zero dipole moment are called polar molecules.Water H2O is a polar molecule due to its bent molecular geometry and the difference in electronegativity between oxygen and hydrogen atoms. Oxygen is more electronegative than hydrogen, which means it attracts the shared electrons in the O-H bond more towards itself. This results in a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. The bent geometry of the water molecule causes these charges to be separated, resulting in a net dipole moment.On the other hand, sulfur hexafluoride SF6 is a non-polar molecule. It has an octahedral molecular geometry, with six fluorine atoms surrounding a central sulfur atom. Fluorine is more electronegative than sulfur, so the shared electrons in the S-F bond are attracted more towards the fluorine atoms, creating partial negative charges on the fluorine atoms and a partial positive charge on the sulfur atom. However, due to the symmetric arrangement of the fluorine atoms in the octahedral geometry, the individual bond dipoles cancel each other out, resulting in a net dipole moment of zero.In conclusion, when a water molecule is replaced by a sulfur hexafluoride molecule, the dipole moment changes from a non-zero value for water to zero for SF6 , as determined by ab initio calculations. This means that the sulfur hexafluoride molecule is non-polar, while the water molecule is polar.