Question

which one of the following is the balanced chemical equation for the reaction of iodide with peroxydisulfate and what type of reaction is this?

a) I₂+2S₂O₃^2--->2I-+ S₄O₆^2-

b) 2I-+S4O6^2--->I2 + 2S2O3^2-

c) S2O8^2-+2I- --> I2 +SO4^2-

d) I2- +2SO4^2---> 2S2O8^2- + 2I-

e) 2I- + 2SO4^2- --> I2+ 2S2O8^2-

acid base

redox

neutralization

precipitation

metathesis

Answer 1

c) S₂O₈^2- + 2I - --> I₂ +SO₄^2- is the balanced chemical equation for the reaction of iodide with peroxydisulfate and this is redox reaction.

Write the 1st half reaction-

S₂ O₈^2- + 2e- <- --> 2SO₄^2-

Reduction is the gain of electrons, here Oxygen atom gain electron. There is decrease in in oxidation state oxygen ion. The oxidation state of the Sulphur is not affected. Overall difference in charge on the oxygen between the peroxodisulfate and sulfate the oxidation state of the oxygen differs between them, and decreased.

Write the 2nd half reaction-

2I---->I₂+ 2e-

Oxidation – I^-is losses of electrons and reduced to I₂.There is also an increase in oxidation state of Iodine -1 to 0.