Chem

__**Chem**__


 * Research Question:** How the pollution affects the amount of dissolved oxygen in the water.
 * Hypothesis:** If the pollution increases in the water the dissolved oxygen content decreases
 * Method:** Determination through Titration
 * Summary of method which i followed:**

I took the water samples and added an excess manganese (II) salt, sodium iodide and hydroxide to form a white precipitate which then oxidized by the dissolved oxygen and turned into brown manganese precipitate. Then I added sulfuric acid to acidify the solution, and now the brown precipitate converts to iodide ion to iodine. The amount dissolved oxygen is directly proportional to the titration of iodine with a thiosulfate solution.

All the solutions that i have used above were made such as the thiosulfate solution. __ Equipment and Materials __

125 mL Erlenmeyer flasks Volumetric Pipette Magnetic Stirrer Glasss toppered flask 3 150ml Beaker 5 Bottles Dropper

Managanous sulphate Sodium iodide Sodium Thiosulphate Potassium iodide Potassium Iodate Sulphuric acid  Sodium hydroxide Manganese chloride