Question

The permanganate ion is often used to analyze for iron (II) ion content in aqueous solutions via the reaction: 8H+ + MnO4- + 5 Fe2+ --> 5 Fe3+ + Mn2+ + 4 H2O. What is the concentration of the Fe2+ solution if 50.00 mL of Fe2+ requires 36.43 mL of 0.025 M MnO4-?

Answer 1

Answer:

0.092 M

Explanation:

Let's consider the following redox reaction.

8 H⁺ + MnO₄⁻ + 5 Fe²⁺ → 5 Fe³⁺ + Mn²⁺ + 4 H₂O

The moles of MnO₄⁻ is:

$36.43 \times 10^{-3} L.\frac{0.025mol}{L} =9.1 \times 10^{-4}mol$

The molar ratio of MnO₄⁻ to Fe²⁺ is 1:5. Then, the moles of Fe²⁺ are:

5 × (9.1 × 10⁻⁴ mol) = 4.6 × 10⁻³ mol

The concentration of Fe²⁺ is:

$\frac{4.6 \times 10^{-3}mol}{50.00 \times 10^{-3} L} =0.092 M$