The chief chemist of the Brite-Metal Electroplating Co. isrequired to certify that the rinse solutions that are discharged from the company’s tin-plating process into the municipal sewer system contain no more than 10 ppm (parts per million) by mass of Sn2+. The chemist devises the following analytical procedure to determine the concentration. At regular intervals, a 100-mL (100-g) sample is withdrawn from the waste stream and acidified to pH = 1.0. A starch solution and 10 mL of 0.10 M potassium iodide are added, and a 25.0-mA current is passed through the solution between platinum electrodes. Iodine appears as a product of electrolysis at the anode when the oxidation of Sn2+ to Sn4+ is practically complete and signals its presence with the deep blue color of a complex formed with starch. What is the maximum duration of electrolysis to the appearance of the blue color that ensures that the concentration of Sn2+does not exceed 10 ppm?
The chief chemist of the Brite-Metal Electroplating Co. is
required to certify that the rinse solutions that are discharged from the company’s tin-plating process into the municipal sewer system contain no more than 10 ppm (parts per million) by mass of Sn2+. The chemist devises the following analytical procedure to determine the concentration. At regular intervals, a 100-mL (100-g) sample is withdrawn from the waste stream and acidified to pH = 1.0. A starch solution and 10 mL of 0.10 M potassium iodide are added, and a 25.0-mA current is passed through the solution between platinum electrodes. Iodine appears as a product of
does not exceed 10 ppm?
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