Iodimetric titrations are usually performed in neutral or mildly alkaline (p H = 8) or weakly acidic solutions. Which statement is not valid for this observation?

Question

Iodimetric titrations are usually performed in neutral or mildly alkaline (p H = 8) or weakly acidic solutions. Which statement is not valid for this observation? (A) In strong alkaline solution, I2 disproportionate to I- and I O- (B) In strong acidic solutions, starch used to detect the end point tends to hydrolyse or decompose (C) I- produced during titration tends to be oxidised by dissolved oxygen in acidic medium (D) Reducing power of reducing agent is increased in strong acidic medium

Tardigrade Admin · Accepted Answer

I2 + 2O H- arrow I O- + I- + H2O H2A s O3 + I2 + H2O arrow H3A s O3 + 2I- + 2H+ (In acidic medium reverse reaction predominates) 4I- + O2 + 4H+ arrow 2I2 + 2H2O

Q. Iodimetric titrations are usually performed in neutral or mildly alkaline $(p H = 8)$ or weakly acidic solutions. Which statement is not valid for this observation?

In strong alkaline solution, $I_{2}$ disproportionate to $I^{-}$ and $I O^{-}$

In strong acidic solutions, starch used to detect the end point tends to hydrolyse or decompose

$I^{-}$ produced during titration tends to be oxidised by dissolved oxygen in acidic medium

Reducing power of reducing agent is increased in strong acidic medium

$I_{2} + 2 O H^{-} \to I O^{-} + I^{-} + H_{2} O$

$H_{2} A s O_{3} + I_{2} + H_{2} O \to H_{3} A s O_{3} + 2 I^{-} + 2 H^{+}$

(In acidic medium reverse reaction predominates)

$4 I^{-} + O_{2} + 4 H^{+} \to 2 I_{2} + 2 H_{2} O$

Q. Iodimetric titrations are usually performed in neutral or mildly alkaline (pH=8) or weakly acidic solutions. Which statement is not valid for this observation?

In strong alkaline solution, I2​ disproportionate to I− and IO−