Even though the titrated solution turned clear, there were blue specks remaining in the vial. What should I do?
A. Swirl the titration vial thoroughly to attempt to dissolve them. It’s possible that the starch indicator has degraded. Report DO at the point the solution became clear, indicate the concern in the comments section and request a replacement starch indicator. Q. What is the chemical reaction that occurs during the dissolved oxygen test?…in layman’s terms please. A. When the first two reagents are added to the water sample (manganous sulfate and alkaline potassium iodide), a white floc or precipitate is created that will eventually sink to the bottom of the sample container, as each oxygen atom binds with a manganese ion to form a manganous hydroxide complex. The addition of sulfuric acid converts manganic hydroxide to manganic sulfate and the iodine is simultaneously oxidized, releasing free iodine into the water (turning the sample a yellow-brown color) in an amount directly proportional to the amount of oxygen present. When sodium thiosulfate is added, it reacts with the free iodine
