Molar masses:
[tex]m_{Fe} = 56g/mol
\\
m_{O} = 16g/mol
\\\\
\therefore m_{Fe_{2}O_{3}} = 2 \cdot (56)+3 \cdot (16) = 112+48 = 160g/mol[/tex]
So:
[tex]1mol \ Fe_{2}O_{3} = 160g = 6 \cdot 10^{23}molecules
[/tex]
160g ---------- 6·10²³molecules
79g ---------- x
x = 2.9625·10²³ molecules
1molecule = 5 atoms
2.9625·10²³ molecules = 2.9625·10²³·5 = 14.8125·10²³ atoms
