Mass of aluminum in the sample is 3.53 g.

Mass of aluminum oxide is 6.67 g.

Step 2

Mass percent of a substance is equal to the mass of a substance divided by the total mass of compound multiplied by 100.

Write the expression of mass percent of aluminum.

\(\displaystyle\text{Mass percent}={\left({\frac{{\text{Mass of Al}}}{{\text{Mass of}{A}{l}_{{{2}}}{O}_{{{3}}}}}}\right)}{100}\%\)

Substitute 3.53 g for mass of Al and 6.67 g for mass of aluminum oxide to calculate mass percent.

\(\displaystyle\text{Mass percent}={\left({\frac{{{3.53}{g}}}{{{6.67}{g}}}}\right)}{100}\%\)

\(\displaystyle={52.92}\%\)

Therefore, mass percent of aluminum is 52.92%.

The answer in three significant figures is 52.9%.