Question

List the color change expected at the equivalence point for each of the possible titrations you might perform in Parts B, C, D.

B. MnO₄^1-(aq) + Fe²⁺ (aq) --> Mn^2-(aq) + Fe³⁺(aq)

C. MnO₄^1-(aq) + H₂O₂(aq) --> Mn²⁺(aq) + O₂ (g)

D. ClO^1- + I^1- + H₃O⁺ --> I₂ + Cl^1- + 3H₂O (starch present)

I₂ + S₂O₃^2- --> I^- + S₄O₆^2- (starch present)

Answer 1

B. MnO₄^1-(aq) + Fe²⁺ (aq) --> Mn²⁺(aq) + Fe³⁺(aq)

color changes from colorless to light purple if titrating Fe²⁺ by MnO₄^- .

C. MnO₄^1-(aq) + H₂O₂(aq) --> Mn²⁺(aq) + O₂ (g)

color changes from colorless to light purple if titrating H_²O₂ by MnO₄^- . Here H₂O₂ is titrated by MnO₄^- and at the end point when 1 drop of excess MnO₄^- is added it show light purple color of MnO₄^-.

D. ClO^1- + I^1- + H₃O⁺ --> I₂ + Cl^1- + 3H₂O (starch present)

Pale yellow to blue-black color. Here the I₂ formed produces blue-black color in presence of starch.

I₂ + S₂O₃^2- --> I^- + S₄O₆^2- (starch present)

Blue-black to colorless solution as Iodine in presence of starch form blue-black coloration and this is due to that I₂ is reduced by S₂O₃^2- to form I^-.