Question

Based on Redox Titration, what do you suggest for the titration of iron()? Choose the titrant, determine the oxidation and reducing agents, write the half-equations, balance the Redox reaction, choose suitable indicators, and describe the type of redox titration (direct or back titration, the medium used, color changes, etc.).

Answer 1

For the titration of iron(II) (Fe²+), a suitable titrant would be sodium dichromate (Na₂Cr₂O7). The oxidation half-equation is: Fe²+ → Fe³+ + e-, while the reduction half-equation is: Cr₂O7²- + 14H+ + 6e- → 2Cr³+ + 7H2O. This is a direct redox titration, using diphenylamine as the indicator in acidic conditions.

Step-by-step explanation:

Based on the information provided, for the titration of iron(II) (Fe²+), a suitable titrant would be sodium dichromate (Na₂Cr₂O7). In this redox titration, the oxidation agent is Na₂Cr₂O7, which is reduced to Cr³+, while the reducing agent is Fe²+, which is oxidized to Fe³+.

The half-equations for this redox reaction can be written as:

Oxidation: Fe²+ → Fe³+ + e-

Reduction: Cr₂O7²- + 14H+ + 6e- → 2Cr³+ + 7H2O

To balance the redox reaction, multiply the oxidation half-equation by 6 and the reduction half-equation by 3:

6Fe²+ → 6Fe³+ + 6e-

Cr₂O7²- + 14H+ + 6e- → 2Cr³+ + 7H2O

The suitable indicator for this titration is diphenylamine, which changes color when the reaction reaches the endpoint. This is a direct redox titration, where the titrant (sodium dichromate) is added directly to the sample solution of iron(II) until the color change occurs.

In terms of the medium used, acidic conditions with the presence of dilute sulfuric acid (H₂SO4) are suitable for this redox titration.

The primary topic of this question is the titration of iron(II) using redox reactions.