Question

A 3.000gram sample of a hydrate compound containing Co, C2O4, and H2O was combusted to give 1.316g of Co3O4. What is the percentage of Cobalt in the original sample?

Answer 1

g Co = 1.316g Co3O4 x (3*atomic mass Co/molar mass Co3O4) = ?
Then %Co = (mass Co3O4/mass sample)*100 = ?