Calculation of Molecular Weight and find out Molecular weight - Sometimes it is also called as Molecular Mass . In order to find out exact M.W. We need two things first molecular formula to find out weight of any compound or chemical and second is a periodic table.
- You must know the molecular formula.
- Second step is to use periodic table to find atomic weight.
- Multiply the atomic weight. Example Oxygen (O2), Here oxygen is present two times hence atomic weight of oxygen given in the periodic table is 16 so now it is multiplied twice , Hence by multiplying we get 16*2=32
- Add up all the atomic weight.
- Molecular mass or molecular weight or the formula weight of a compound will be the final result obtained after summation.
- H2O- Water, We know that atomic weight of H is 1 hence 2*1=2, Now atomic weight of Oxygen is given in periodic table is 16 Just add up atomic weights i.e., 2+16=18 Hence Molecular weight of Water is 18g/Mol
- In the same way For H2SO4 . The weight is found 2+32+4*16=98 g/mol. Here atomic weight of hydrogen is 2 for sulphur is 32 and oxygen having 16*4 as there are 4 times oxygen is present. Hence by adding all the atomic weight we get 98g/mol