A compound was found to contain copper and chlorine. The mass of the compound was 351 mg. The amount of copper in the sample was found to be 225 mg. What is the empirical formula for the compound?

Answer 1

So if the mass of the compound is 351 mg the mass of chlorine is (351-225) mg = 126 mg

Thus number of moles of Cu =mass/RAM

Thus number of moles of Cl =mass/RAM

divided by smallest number of moles to get the ratio.

I'll let you work it out.