Question

How many moles of ferric alum (NH4
)2
SO4
·
Fe2
(SO4
)
3
·24H2

O can be made from the sample

of Fe containing 0.0056 g of it ?

[Atomic mass of Fe = 56 u]

(1) 10–4 mol (2) 0.5 × 10–4 mol

(3) 0.33 × 10–4 mol (4) 2 × 10–4 mol

Answer 1

112g of Fe is contained in---->1 mole of ferric alum

therefore 5.6 * 10^-3g of Fe will be in ----->(1/112)*5.6*10^-3

=====> 0.5 * 10^-4 mol.of ferric alum.

The ans. is (2) 0.5 * 10^-4


Hope it helps.