A 4.94-g sample of an oxide of chromium contains 3.06 g of chromium. Calculate the simplest formula for the compound.

CrO2

Explanation:

Firstly, we need to find the mass of the oxygen in the oxide. That is 4.94 - 3.06 = 1.88g

Now, we will need to get the number of moles and this can be obtained by dividing the masses by the atomic mass units. The atomic mass units of chromium and oxygen are 52 and 16 respectively. The division is obtained as follows:

Cr = 3.06/52 = 0.06

O = 1.88/16 = 0.12

We then divide by the smallest, which is that of the chromium.

Cr = 0.06/0.06 = 1

O = 0.12/0.06 = 2

The simplest formula is the empirical formula and it is thus given by CrO2