Writing Ionic Formulas, Given the ions

1. The problem statement, all variables and given/known data

Potassium chromate is an important compound of chromium. It is composed of K⁺

and CrO₄^2-. Write the formula of the compound.



2. Relevant equations

positive charge + negative charge = 0





3. The attempt at a solution

I know how to do this problem by cross switching the charges but I want to know how to do it by finding the ratio. So what I tried to do was say that it takes 8 K to equal the negative charge of the CrO₄ so the ration is 8:4. That means K₈ = CrO₄. Then I reduced and got K₂ = CrO. The correct answer is K₂ = CrO₄.