How many grams of O are in 635 g of Li 2 O?

340g

Explanation:

Lithium oxide or Li2O is an inorganic compound made of two lithiums and one oxygen molecules. Lithium molecular mass is 6.94g/mol while oxygen molecular mass is 16g/mol. The molecular mass of Li2O will be:

2 * 6.94g/mol + 1*16g/mol = 29.88g/mol

Out of 1 mol lithium oxide (29.88g), there is 1 mol of oxygen (16g). Then, out of 635g lithium oxide the number of oxygen will be: 635g * (16g/29.88g) = 340g