# The white powder often found on objects made of aluminum is aluminum oxide, AI_2O_3. Calculate...

## Question:

The white powder often found on objects made of aluminum is aluminum oxide, {eq}AI_2O_3. {/eq} Calculate the molar mass of the aluminum oxide. If you wanted to make a molar quantity of aluminum oxide in the laboratory, how many grams of aluminum would you need to begin with?

## Molar Mass

Molar mass is the mass of a given chemical element or chemical compound divided by the amount of substance. It has a unit of grams per mole.

Note that the molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.

Chemica formula for aluminum oxide is {eq}Al_2O_3 {/eq}

Calculating molar mass

Al: 2 x 27 = 54

O: 3 x 16 = 48

Therefore, {eq}Al_2O_3 {/eq} has a molar mass of 102 grams per mole.

Calculating mass of aluminum (molar mass = 27)

{eq}mass\,Al = 1\,mol\,Al_2O_3 \times \dfrac{2\,moles\,Al}{1\,mole\,Al_2O_3} \times 27\dfrac{g}{mole} = 54\,grams\,Al {/eq}