Another Gravimetric problem

a 1.345g sample of a compound of barium and oxygen was dissolved in hydrochloric acid to give a solution of barium ion, which was then precipitated with an excess of potassium chromate to give 2.012g of barium chromate, BaCrO4. what is the formula of the compound.

I have worked the problem out, but not sure if I did it right.

(2.012 g BaCrO4)/(253.3216 g BaCrO4/mol)*(1 mol Ba/1 mol BaCrO4)*(137.3277 g Ba/mol) = 1.091 g Ba

(1.345 g sample) - (1.091 g Ba) = 0.254 g O [oxygen]

(1.091 g Ba)/(137.3277 g Ba/mol) = 0.0079445 mol Ba

(0.254 g O)/(15.99943 g O/mol) = 0.0158756 mol O

(0.0079445 mol Ba)/0.0079445 = 1.00 --> Ba

(0.0158756 mol O)/0.0079445 = 2.00 --> O

Answer:

the formula of the compound is BaO2, barium peroxide.

Bye,

C6H6