Answer to Question #163341 in General Chemistry for mike

Question

Sodium iodate reacts with sodium sulfite according to the equation :

NaIO3    +    3Na2SO3     →     3Na2SO4    +    NaI

a). In this reaction, which substance is the oxidising agent? Why?

b). How many grams of NaIO3 are needed to react with 5.00g of Na2SO3?

Answer 1

a. NaIO₃ is the Oxidizing agent.

The reason is that the Oxidation number of Iodine changes from +5 in NaIO₃ to -1 in NaI. This shows that the compound itself undergoes reduction (as an oxidizing agent)

b. Molar mass of NaIO₃= 198g/mol

Molar mass of Na₂SO₃= 86g/mol

From the equation

3(86)g of Na₂SO₃ reacts with 198g of NaIO₃

5.00g of Na₂SO₃ will react with

198 x 5.00/258 = 3.84g of NaIO₃