Oxygen's atomic weight is 16.00 amu. 1 mole of oxygen is 6.02 x 1023 atoms of oxygen 1 amu = 1.661 x 10-24g What is the molar mass (g/mole) of oxygen? Molar mass (in grams) is always equal to the atomic weight of the atom! Molar mass (in grams) is always equal to the atomic weight of the atom!
It has to be 120g because each and every chemical equation has to satisfy the law of conservation of mass, ie sum of mass of products is always equal to the sum of masses of reactants. If reactants=120g, then products=120g
