The basic principle in balancing a chemical equation is to

obey the law of conservation of mass.

Explanation:

The law of conservation of mass states that matter can not be created nor be destroyed but can be transformed from one form to another. Whenever one balance an equation, if the equation is not balance it means something has be destroyed or created, this we give an ideal that the equation is not balance or wrong.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.