Biological oxygen demand (BOD) of water sample analysis Essay

Qualitative data gathered sample was very murky The root end point colour was of a yellow colour, perhaps not conflagrate enough Addition of starch forefinger produced a grey-black solution perhaps did not add enough indicator, however this did not pose as a trouble There was one occasion where I suspected to have added too frequently(prenominal) sodium thiosulphate, however the second exam indicated that I did not go retiring(a) the end point too muchCalculationsTo calculate the dissolved atomic number 8 gist (mg/dm or ppm), we must basic determine the consequence of mols of thiosulphate from the mean titrated wad of both samples. In this case, we will wont sample A.The Winkler method indicates that the relationship amid the amount of oxygen and thiosulphate is a tetrad to one ratio. Therefore, we will divide the go of mols of thiosulphate by four to get the number of mols of oxygen. and then we convert this to milligrams per dm introductory by multiplying by 20 to pass with the number of mols present in 1dm (because the pool water sample used was 50cm). accordingly 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 molarity to be converted into milligrams.The biological oxygen demand (BOD) would therefore be the divergency between the DO of sample A and sample B.