1. Mg + 1/2O2 => MgO
24g Mg......................40g MgO
120g Mg......................xg MgO
x=120*40/24 =
MMg=24g/mol MMgO=40g/mol
2. CaO + H2O => Ca(OH)2
56kg CaO.............18kg H2O
44,8kg CaO...........x kg H2O
x=18*44,8/56 =
MCaO=56kg/kmol MH2O=18kg/kmol