Q7(a). Cerimetric titration of iron
Consider the redox titration of Fe²⁺ ion by Ce⁴⁺ ion in dilute H₂SO₄ medium at 298 K: Ce⁴⁺ + Fe²⁺ ⇌ Ce³⁺ + Fe³⁺. Calculate the equilibrium constant of the above reaction. Comment on the feasibility of the above titration. Draw the titration curve and suggest a suitable indicator to detect the equivalence point of the titration. [Given: Ce⁴⁺ + e⁻ ⇌ Ce³⁺, E°=1.44 V; Fe³⁺ + e⁻ ⇌ Fe²⁺, E°=0.77 V.]
Answer in brief
K≈2.1×10¹¹; the reaction is sufficiently quantitative for titration. Ferroin is a suitable indicator; the ideal equivalence potential is about 1.105 V.
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CoversCerimetric titration of ironRedox equilibria and indicators
All parts of Question 7
- 7(a) Cerimetric titration of iron15 marks
- 7(b) Nickel–cobalt displacement15 marks