What is the molar mass of lithium oxide, #Li_2O#?
atomic weight of element
First, you want to have your handy dandy periodic table available so you can determine the atomic weight of Li and O:
Li has an atomic weight of 6.94 g/mol
O has an atomic wight of 16.00 g/mol
Based on the chemical formula, we have 2 atoms of Li, so the atomic weight of Li has to be multiplied by 2 to obtain 13.88 g/mol.
You have 1 atom of O, so the atomic mass would just be 16.00 g/mol
Now you want to add the mass of each atom together to obtain the molar mass of the entire compound:
If you refer to your periodic table, the atomic weight is the molar mass of each element.
The molar mass of Lithium is 6.9 g/mol and Oxygen 16.0 g/mol.
Since there are 2 atoms of Lithium - if you look closely in
the molar mass of lithium
Add the molar masses of Lithium and Oxygen together:
13.8 g/mol + 16.0 g/mol therefore the molar mass of Lithium oxide is 29.8 g/mol.