The Winkler method may be used to determine the concentration of DO in a sample of water. In the reaction, 1mole of oxygen produces 2 moles of iodine. The iodine is then titrated with Na2S2O3, using starch as an indicator, according to the equation:
I2 + 2Na2S2O3 --> 2NaI + Na2S4O6
A 500 mL...