Question

16-33. Potassium bromate, KBrOs, is a primary standard for the generation of Br2 in acidic solution: BrOS + 5Br_ + 6H+-3Br2(aq) + 3H20 The Br2 can be used to analyze many unsaturated organic com- pounds. Al3+ was analyzed as follows: An unknown was treated with 8-hydroxyquinoline (oxine) at pH 5 to precipitate aluminum oxinate, AIC,H,ON)3. The precipitate was washed, dissolved in warm HCl containing excess KBr, and treated with 25.00 mL of 0.020 00 M KBrO3. OH 2Br2 Br Он +2H+2Br он The excess Br2 was reduced with KI, which was converted into I The I3 required 8.83 mL of 0.051 13 M Na2S20s to reach a starch end point. How many milligrams of Al were in the unknown?
Correct answer is 5.730mg but do not know how to get that answer