Question

How many mL of a 100 mg/dL Ferrozine solution are needed to complex 5.5×10−8 moles of iron?

How many moles of Fe3+ can be reduced by 1.1 mL of 0.216 M hydroxylamine solution?

As part of this laboratory, you may have to add iron to a solution. If you have 20 mL of a solution that contains 47 μg dL-1, how many mL of 500 μg dL-1 iron must be added to reach a concentration of 150 μg dL-1?

Answer 1

Ans 1

Balanced chemical equation

[Fe(H2O)6]+2 + 3(FerroZine)-2 -----> Fe(FerroZine 3)-4 + 6H2O

1 mol of Fe requires = 3 mol of FerroZine

5.5×10−8 mol of Fe requires = 3 x 5.5 x 10^-8

= 16.5 x 10^-8 mol of FerroZine

Molecular weight of FerroZine = 514.438 g/mol

Mass of FerroZine = 16.5 mol x 10^-8 x 514.438 g/mol

= 8488.227 x 10^-8 g =8488227 x 10^-8 mg

Volume require = 8488227 *10^-8 mg / 100 mg/dL

= 84882.27 *10^-8 dL x 100 mL /dL

= 0.0848mL

Ans 2

Hydroxylamine reduces Fe3+

2NH2OH + 4 Fe3+→N2O(g) ↑ + H2O + 4 Fe2+ + 4H+

Moles of hydroxylamine solution = 0.216 x 1.1/1000

= 0.0002376 moles

Moles of Fe3+ = 4 mol Fe3+ x 0.0002376/2

= 0.0004752 mol