Biological oxygen demand (BOD) of water sample analysis Essay

Qualitative data Collected ideal was real murky The first end point colour was of a jaundiced colour, perhaps not light enough Addition of starch exp one(a)nt produced a grey-black solution perhaps did not add enough indicator, nevertheless this did not pose as a problem There was one occasion where I suspected to have added too much sodium thiosulphate, however the second trial indicated that I did not go preceding(a) the end point too muchCalculationsTo calculate the dissolved oxygen content (mg/dm or ppm), we must first determine the proceeds of mols of thiosulphate from the mean titrated volume of both essays. In this case, we will use sample A.The Winkler method indicates that the relationship between the amount of oxygen and thiosulphate is a quaternion to one ratio. Therefore, we will divide the number of mols of thiosulphate by four to overreach the number of mols of oxygen.Then we convert this to milligrams per dm first by multiplying by 20 to arrive with the numb er of mols present in 1dm (because the pond water sample used was 50cm). Then we multiply that number by 32 (molecular mass of oxygen) to attain the number of grams of oxygen. Then finally, the number is multiplied by 1000 to be converted into milligrams.The biological oxygen demand (BOD) would wherefore be the difference between the DO of sample A and sample B.