The electrolysis of an aqueous solution of potassium iodide, KI, results in the formation of hydrogen gas at the cathode and iodine at the anode. A sample of 80.0 millilitres of a 0.150 molar solution of KI was electrolyzed for 3.00 minutes, using a constant current. At the end of this time, the I2 produced was titrated against a 0.225 molar solution of sodium thiosulfate, which reacts with iodine according to the equation below. The end point of the titration was reached when 37.3 millilitres of the Na2S2O3 solution had been added. I2 + 2S2O32 - rightarrow 2I - + S4O62 -
1. How many moles of I2 was produced during the electrolysis?
2. The hydrogen gas produced at the cathode during the electrolysis was collected over water at 20 degree C at a total pressure of 752 mmHg. Determine the volume of the hydrogen gas collected. (The vapor pressure of water at 25 degree C is 24 mmHg.)
3. Write the equation for the half reaction that occurs at the anode during the electrolysis.
4. Calculate the current used during the electrolysis.