What is the percent composition of O in Aluminum Sulfate?

There is 9.2758% Al3+ in a formula unit of aluminum oxide.

AnswerThe formula for aluminum oxide is Al2O3: Molar mass =581.77g/mol Al2O3.

In one mole Al2O3, there are two moles of Al3+ ions, therefore 2 moles Al3+ x 26.982g/mol Al3+ = 53.964g Al3+ in one mole of Al2O3.

GIVEN: mass of Al3+ = 53.964 gAl3+;Molar mass of Al2O3 = 581.77 gAl2O3

WANTED: % Al3+

EQUATION:

% Al3+...=...g Al3+x 100...g Al2O3

% Al3+...=...53.964gAl3+x100......=...9.2758%Al3+581.77g Al2O3