mass of pentane = 22.5g
molar mass of pentane(C5H12) = 5 x 12.01 + 12 x 1.008
= 60.05 + 12.096
= 72.146g/mol
= 72.15g/mol
22.5g pentane x 1 mol pentane x 6.022 x 10^23 molecules ofpentane
72.15g pentane 1 mol pentane
= 22.5 x 6.022 x 10^23
72.15
= 1.88 x 10^23 pentane molecules
1 pentane molecule has 5 C + 12 H atoms = 5+12 = 17 atoms
Hence;
1.88 x 10^23 pentane molecules x 17 atoms
1 pentane molecule
= 31.925 x 10^23 atoms
= 3.2 x 10^22 atoms are present in 22.5g of pentane.
3.2 x 10^22 atoms