Question

What volume of 0.4 molar FeCl3.6H2O will contain 600 milligrams of Fe3+​

Answer 1

Answer:

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• Molar mass of FeCl3.6H2O = 55.85 + 35.45 x 3 + 18 x 6 = 270.2 gm

• Amount of the salt in 1 litre of 1M solution = 270.2 gm

• Amount of the salt in 1 litre of 0.4M solution = 270.2 x 0.4 =108.1 gm

• Atomic mass of iron (Fe) = 55.85 u; Molar mass of iron = 55.85 gm.

• One mole of FeCl3.6H2O contains only one mole of Fe3+ (iron). That is, 270.2 gm of the salt contains 55.85 gm of iron (Fe3+).

• Amount of Fe3+ (iron) in 1 litre of 0.4M solution = 108.1 x 55.85/270.2 = 22.34 gm.

• So, 1 litre (1000 ml) of the 0.4M salt solution contains 22.34 gm of Fe3+ (iron).

• Volume needed for 600 mg (0.6 gm) of Fe3+ = 0.6 x 1000/22.34 = 26.9 ml.