How do you find the empirical formulas for 65.2% Sc, 34.8% O?

1 Answer
Mar 4, 2017

As with all these problems, we ASSUME a 100g mass of compound.........and come up with an empirical formula of Sc2O3.

Explanation:

The empirical formula is the simplest whole number ratio defining constituent atoms in a species. We assume a 100g mass of Sc2O3, and we come up with a molar ratio:

Moles of scandium = Mass of scandiumMolar mass of scandium = 65.2g44.96gmol1=1.45mol.

Moles of oxygen = Mass of oxygenMolar mass of scandium = 34.8g16.00gmol1=2.175mol.

In each instance, I divided thru by the ATOMIC MASS of the element. And now if we divide thru by the smallest molar quantity, (that of the metal), I get a formula of ScO1.5. Because, by specification, the empirical formula is a WHOLE number ratio, we quote its empirical formula as Sc2O3. Capisce?