Determination Of Dissolved Oxygen

Determination of DO & BOD in a weewee system system try out © KCl      http://hk.geocities.com/fatherofchemistry Objective            apply volumetrical analysis, the amount of fade out group O (DO) in a body of water sample mass be found. On standing another sample for 5 days, the residuum among these two places is defined as biochemical atomic numerate 8 demand in 5 days (BOD5). The aquatic life needs certain amount of DO for survival, whereas the take account of BOD reflects the water quality. Principle            In alkalescent solution, dissolved oxygen will oxidize manganese(II) into manganese(III):                         4Mn2+(aq)   +   8OH-(aq)   +   O2(aq)   +   2H2O(l)   â†Â Â  4Mn(OH)3(s)               The amount of DO c an be found by titrating the iodine produced from potassium iodide by manganese(III) with atomic number 11 thiosulphate:                        2Mn(OH)3(s)   +   2I-(aq)   +   6H+(aq)   â†Â Â  2Mn2+(aq)   +   I2(aq)   +   6H2O(l)                          I2(aq)   +   2S2O32-(aq)   â†Â Â  2I-(aq)   +   S4O62-(aq) Chemicals          water sample, MnSO4, conc.H2SO4, alkaline KI, hackneyed Na2S2O3, starch solution Apparatus          titration apparatus, pipette, 250cm3 volumetric flask x2, beaker, droppers, magnetic stirrer, white tile Procedure          1.> Collect a water sample with two 250cm3 volumetric flasks. Remember to fill the flasks exclusively with water wit hout trapping any publicise bubbles.  Ã! ‚ Â Â Â Â Â Â  2.> To one of the volumetric flask, land about 1 cm3 of MnSO4 solution well under the issue with a dropper.          3.> Similarly, introduce about 1 cm3 of alkaline KI solution to the same flask. Be sure that no air becomes entrapped and then invert the stopped                flask to run out the precipitate uniformly.          4.> When the precipitates has...If you necessity to get a full essay, dedicate it on our website: BestEssayCheap.com

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