2lab7 - JessicaGaboriault 4/16/08 LabPartnerJackieLerea...

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Jessica Gaboriault 4/16/08 Lab Partner – Jackie Lerea Section A Tuesdays at 2 pm Hutch 115 Experiment 7  – Determination of Dissolved Oxygen in Water Purpose :  The purpose of this experiment is to standardize (determine the concentration of) the  sodium thiosulfate solution, determine the amount of dissolved oxygen in the Genesee River  water, and measure the amount of dissolved oxygen in oxygen – saturated room temperature tap  water. Procedure : see revised experimental procedure handout. Data and observations : PART A - 20 mL sodium thiosulfate solution - Weigh 2.00 g KI - 10 mL H 2 SO 4  at 2 mL - When we mixed 20 mL of potassium dichromate solution into the flask, the color turned  from yellow to orange - When the thiosulfate was added   color turned back to yellow - Added starch   intense blue color - Titrated with 20.0 mL to get the color back to clear (equivalence point) PART B - Tap H 2 O temperature was 21°C - When we mixed the Winkler III solution, the solid went away and it turned an orange  color
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- Solution turned light yellow when 4 mL of titrant was added. -
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2lab7 - JessicaGaboriault 4/16/08 LabPartnerJackieLerea...

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