Question

Calculate the mass% of O in a molecule of aluminum oxide, Al2O3.

Answer 1

which are present in 1 mole of an atom mass of 1 mole of an oxygen atom is 15.99 g/mol ≈16 g/mol

Therefore

1 mole of oxygen= 16 g

6.022×10^23 atoms of oxygen=16 g

1 atom of oxygen= 16÷6.022×10^23 g

1 atom of oxygen=2.65692461×10^-23

Thus mass of one oxygen atom is 2.65692461×10^-23