lab 11 by wkzh0g4J


									Lab 11. Electrolytic cell

Prelab assignment (15 points)

    Insert the following items in your lab notebook; to be done prior to the lab !

             Purpose
             MSDS: none

    questions    [15 points]

              1. In an electrolytic cell (a pair of copper electrodes in a solution of copper (II) nitrate
              connected to a power supply), the current was 0.500 Amperes and its duration was 10.0
              minutes, whre 0.10 g of copper was lost on one of the electrodes. Based on the preceding
              experimental results, determine the value of
                  a. Faraday’s constant, i.e. the number of coul per mole of electrons
                  b. Avogadro’s number (the charge of an electron = 1.6022 * 10 -19 Coulombs)
                  c. calculate the % error in your determination of Faraday’s constant & Avogadro’s


          Based on the charge of an electron (see above) and your experimental results, determine Faraday’s
          constant, then Avogadro’s number. Calculate the % error for your determination of Faraday’s
          constant and Avogadro’s number.

          Compare, i.e. use statistical analysis to determine if there is a difference between ___
                 o magnitude (i.e. absolute value) of the change in the mass of the cathode versus anode
                 o using experimental data from both electrodes
                             experimental value of Faraday’s constant versus its accepted value
                             experimental value of Avogadro’s number versus its accepted value

revise methods: (i) maintain a constant current rather than measuring it very minute, (ii) use a 0.1 mg
analytical balance rather than 1.0 mg balance

Lab report content [35 points]

          Data analysis; show calculations [15 points]
                  o Change in mass of the cathode & anode
                  o Experimental determination of the value of (F) Faraday’s constant; include % error
                  o Experimental determination of the value of (No) Avogadro’s number; include %

          Statistical analysis: see purpose; include your conclusions – refer to statistics to support your
          statements; 15 points]

          Error analysis: rationalize any difference in the accuracy in determining the value of F and No
          between the cathode versus anode. If there is no difference, then provide a plausible, nontrivial
          error that could introduce a systemic error. [5 points]

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