Calculate the number of moles in the following:
(a) 7.85 g of iron, (b) 4.68 mg of silicon
( c) 65.6 `mu`g of carbon.

Explanation

(a) 7.85 g of iron.
Atomic mass of Fe = 55.8 u
Mole of iron `=("Mass of iron")/("Atomic mass")`
`=(7.85)/(55.8) = 0.141` mol
(b) 4.68 mg of silicon `=4.68 xx 10^(-3) g` of silicon
Atomic mass of silicon = 28.1
Moles of silicon `=("Mass of silicon")/("Atomic mass")`
`=(4.68 xx 10^(-3))/28.1`
`=1.66 xx 10^(-4)` mol
( c) `65.6 mug` of carbon `=65.6 xx 10^(-6)` g of carbon
Atomic mass of carbon = 12
Molecules of carbon `=("Mass of carbon")/("Atomic mass")`
`=(65.6 xx 10^(-6))/12`
`=5.47 xx 10^(-6)` mol