EXPERIMENTAL Part A obtain four 50 mL beakers and label them Noala, 1 M cusou, o

Question

EXPERIMENTAL Part A obtain four 50 mL beakers and label them Noala, 1 M cusou, o.1 M cusou, and Feso. respectively. Using a clean graduated cylinder, transfer 30 mL of 1 MZn(NOs)2 solution into the beaker labelled zn(NO)2. Thoroughly rinse out the graduated cylinder with distilled water. Rinse a second time. Repeat this process to transfer 1 M cusou o.1 Mcuso. and 1 M Feso4to each of their respective beakers. Why is the use of clean glassware so important for these measurements? obtain 1 zinc plate, 2 copper wires, and 1 iron plate along with a piece of sand paper. Clean the surface of each of these electrodes with the sandpaper. Be sure to sand all sides of the electrodes and the entire length. Do NOT SAND DIRECTLY ON THE LAB BENCH. Place the from electrode on a piece of scrap paper prior to sanding in order to protect the bench surface scratches. When you have finished sanding, wipe the electrode with a damp paper towel to remove the dust particles followed by a dry paper towel. Record the appearonce of thedean electro Set up the electrochemical cells according to Figure 1 using the 1 M zn(NO,)z solution as the lu, o anode and the 1 M Cusoa solution as the cathode. Put zinc electrode in the zinc solution and the copper electrode into the copper solution. Do the bridge yet. At this not attach the salt point you are ready to connect the multimeter to the cells. Turn the multimeter dial to "DCV Connect the black alligator clip (connected to the negative terminal of the multimeter)to the Zn electrode plate and the red alligator clip (connected to the positive terminal of the multimeter) to the copper wire. What voltage do you observe? Why? Place a strip of filter paper obtain 50 mL of 0.5 M. KNOs and transfer to a 250 mL beaker. it to soak thoroughly. This (provided at the front by the TA) into the KNOs solution and allow do not allow this paper to filter paper will act as the salt bridge. It is very important that you dry, re-soak it in the KNOh dry out at any time during the experiment!!! lf the paper becomes solution.

Explanation / Answer

1. The theoretical voltage is given by Nernst equation. While the actual voltage which is measured depend also on the current (V=iR). Hence various parameters that can lead to variation in resistance can lead to voltage drops e.g.

Salt bridge offers resistance and hence can cause voltage drop

Impurities in metals used for cathode or anode can cause voltage change

Surface coatings may lead to voltage drop.

2

a = 0.185

b = 0.912

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