The total sum of the masses of the atoms or elements present in the molecule is termed as molecular mass.
Calculation of Molar mass of a compound
We can find the molecular mass of the molecule by following the given substance:
- Identify the formula of the compound or molecule
- Using the formula determine the number of atoms present in each element of the compound or molecule
- Multiply the atomic weight of each element with the number of atoms of that particular element
- Similarly, do it for all the elements in the molecule or compound
- Add up all the values obtained in the above step
- Then add the unit as grams/mole you will get the molecular mass of the substance
Molar mass of water
One mole of H2O is made up of 2 moles of hydrogen atoms and 1 mole of oxygen atom.
Molar mass of atoms
Mass of 1 mole of Hydrogen atoms= 1 g /mol
Mass of 1mole of Oxygen atoms = 16 g/mol
Mass of two moles of Hydrogen atoms = 2x 1 g/mol = 2 g/mol.
Mass of one mole of Oxygen atoms = 1 x 16 g /mol
On adding all the above-obtained values we get,
Mass of one mole of water = 2 g/mol + 16 g/mol = 18 g/mol.
Molar mass of water = 18g/mol