What is the molar mass of lithium oxide, Li_2O?

2 Answers
Jul 13, 2016

color(red)("29.88 g/(mol))

Explanation:

color(purple)"Let's use this equation to answer the question:"

atomic weight of element xxnumber of atoms given by subscript = molar mass

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:

color(red) ("13.88 g/mol + 16.00 g/mol = 29.88 g/mol")

Jul 13, 2016

Li_2O is composed of Lithium and Oxygen atoms.

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 Li_2O,
the molar mass of lithium Li_2O is 6.9 xx 2 = 13.8 g/mol.

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.