Question

A metallic oxide is 36.81% oxygen. The metal has a 4+ charge. What is the metal?​ Please include charges in your answer.

Answer 1

The empiric formula is MO2 because oxygen has a 2- charge ( so metal oxidation state is +4)

Out of it's molar mass, 36.81% is oxygen.
So for one mole of the oxide, we have 2 moles of oxygen atoms:
2*(molar mass of oxygen)=2*16=32 grams of oxygen
Which are 36.81% of the total mass.
Total mass = 32*(100/36.81) => 86.93 g
So metal weight = 86.93 - 32 = 54.93 g

Now look for a metal with a molar mass of about 54.93 in the periodic table
It is Mn (Manganese).
Answer is Mn^4+

(MnO2).