Determination of Dissolved Oxygen in a Water Sample Essay

To perplex out the oxygen content of a water type by adding MnSO4 and alkalic KI into the response. Mn2+ was oxidized into Mn3+. Then Mn3+ was reduced back into Mn2+ and I- was oxidized to I2. The solution was titrated against atomic number 11 thiosulphate solution and the oxygen content could be calculated.Result mental testing1Trial2Final burette recital (cm3)19.2638.4219.8238.35Initial burette reading (cm30.1019.500.7419.82 volume of Na2S2O3 added (cm3)19.1618.9219.0818.53Data being used for computingCalculation nary(prenominal)of moles of Na2S2O3 used =2S2O32- + I2 > S4O62- + 2I- zero(prenominal) of moles of I2 in cytosine cm3 solution = = 1.18252Mn(OH)3 + 2I- + 6H+ >I2 + 2Mn2+ + 6water systemNo. of moles of Mn(OH)3 in 100 cm3 solution = 1.1825 X 2 = 2.3654 Mn(OH)2 + O2 + 2 H2O 4 Mn(OH)3No. of moles of O2 in 100 cm3 solution = 2.365Oxygen content = 18.92 mg dm-3DiscussionReason of filling the altogether volumetric flaskfulDuring the experiment, the water sample was allowed to fill with the whole volumetric flask, this is because we charter to prevent oxygen from dissolving from the nimbus into the water sample.Reason of using a magnetic stirrerWhen conducting the experiment, insoluble manganese (III) hydroxide was formed. It would dissolve in grand iodide so we have to use a magnetic stirrer to speed up the reaction process. As a magnetic stirrer could stir the solution without spilling, it is really good to be used in this situation.Source of errorAs the manganese (II) sulphate and potassium iodide solution was added into the flask with over flowing. There pass on be loss of solution in this process. The chemicals added office be not enough and it will affect the experiment result.We cannot avoid oxygen in air from dissolving into the solution as the mouth of volumetric flask could still allow oxygen to dot in.Only one set of entropy could be used beside trials.