Something is still wrong with this equation though. The law of conservation of mass
states that we cannot create or destroy
atoms in a chemical reaction.
Count the number of atoms of chlorine on
each side. What is wrong?
Nothing is wrong. The reaction destroyed a
chlorine atom.
The number of chlorine atoms is different. Since
we cannot create or destroy atoms something is

Cause its being chemically applied?

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.