Step-by-step explanation:
The molar mass of a compound is defined as the mass in grams of one mol of that substance. Its units are [g/mol].
Problem: Calculate the molar mass of H₂O.
The first step to find the molar mass of any compound is to look for the atomic mass of the elements present in the molecule.
atomic mass of H = 1.01 amu
atomic mass of O = 16.00 amu
Then the molar mass of 1 mol of atoms of each element will be the same number but we have to replace the unit amu (atomic mass unit) by g/mol.
molar mass of H = 1.01 g/mol
molar mass of O = 16.00 g/mol
Since one molecule of H₂O has two atoms of H and one atom of O. One mol of H₂O molecules will have 2 moles of H atoms and 1 mol of O atoms. So the molar mass of H₂O will be:
molar mass of H₂O = 2 * molar mass of H + 1 * molar mass of O
molar mass of H₂O = 2 * 1.01 g/mol + 1 * 16.00 g/mol
molar mass of H₂O = 18.02 g/mol
Answer: the molar mass of H₂O is 18.02 g/mol