The Peroxydisulfate Ion (S₂O₈^2-)reacts with the Iodide Ion in Aqueous

question 106

Multiple Choice

The peroxydisulfate ion (S₂O₈^2-) reacts with the iodide ion in aqueous solution via the reaction:
S₂O₈^2- (aq) + 3I^- → 2SO₄ (aq) + I₃^- (aq)
An aqueous solution containing 0.050 M of S₂O₈^2- ion and 0.072 M of I^- is prepared, and the progress of the reaction followed by measuring [I^-]. The data obtained is given in the table below.
-The average rate of disappearance of I^- in the initial 400.0 s is ________ M/s.

• A)6.00
• B)3.8 × 10^-5
• C)1.4 × 10^-4
• D)2.7 × 10⁴
• E)3.2 × 10^-4