A sample of a compound contains 7.89 g potassium, 2.42 g carbon, and 9.69 g oxygen. Determine the empirical and molecular formulas of this compound, which has a molar mass of 198.22 g/mol.

The empirical formula of the compound =

The molecular formula of the compound =

Explanation:

Mass of potassium = 7.89 g

Molar mass of potassium = 39 g/mol

Moles of potassium =

Mass of carbon  = 2.42 g

Molar mass of carbon = 12 g/mol

Moles of carbon =

Mass of oxygen = 9.69 g

Molar mass of oxygen = 16 g/mol

Moles of oxygen =

For the empirical mass of the compound, divide the lowest moles of an element with all the moles of the elements:

Potassium :

Carbon :

The empirical formula of the compound =

Empirical mass of the compound= (39 g/mol+12 g/mol+3 × 16 g/mol) = 99 g/mol

Molar mass of the compound = 198.2 g/mol

Let the molecular formula of the compound be :

So, molecular mas of the compound :