Chlorine gas has a molar mass of 70.90 g/mol. Two chlorine atoms combine to form a single chlorine molecule, which has the chemical formula Cl2.
The Periodic Table of Elements indicates that the molar mass of one chlorine atom is 35.45g/mol. Simply sum the molar masses of the two chlorine elements, or multiply the atomic mass by two, to get the molar mass of one chlorine molecule.
Thus, the molar mass of chlorine gas is 35.45g/mol multiplied by two to equal 70.90g/mol. Chlorine is a gas in its natural state, but it can be cooled and transformed into a liquid for storage and transit. It returns to its original gas condition after being discharged.