Explanation:
Percentage of an element in a compound:
[tex]\frac{\text{Number of atoms of element}\times \text{Atomic mass of element}}{\text{molecular mass of compound}}\times 100[/tex]
Molecular mass of [tex]Cr_2O_3[/tex] = 152 g/mol
Percentage of chromium:
Number of chromium atoms = 2
Atomic mass of chromium = 52 g/mol
[tex]\frac{2\times 52g/mol}{152g/mol}\times 100=68.42\%[/tex]
Percentage of oxygen:
Number of oxygen atoms = 3
Atomic mas of oxygen = 16 g/mol
[tex]\frac{3\times 16g/mol}{152 g/mol}\times 100=31.58\%[/tex]
The percent composition of Cr in [tex]Cr_2O_3[/tex] is 68.42%.
The percent composition of O in [tex]Cr_2O_3[/tex] is 31.58%.
