Question

Part B - Electrochemical Cells Red Multimeter Wire cu Fe ΑΙ Voltage XXN 43 +0.47 Current +1.06 +00.2 1+0.59 +0.02 +00.0 1-0.01 100.0 Black Multimeter Wire 1-0.61 Voltage 1-43 Current 0.00 Voltage - 1.06 Current -00.2 1-00.1 Voltage-4.45 1+0.02 Current Current -00.0 10.0 1-0.63 1-00.1 х Voltage IX | +0.61 1+00.1 **Part B Multimeter settings: Voltage 20 DCV, current 200m DCA

in part of the experiment, you measure each metal combination twice, but the red and black leads of the meter were switched for each test. compare the voltages of each metal combination. what pattern do you see in the voltages depending on which way the red-black leads or the multimeter are connected to the metals? why do you think you saw a pattern in these voltages?

Answer 1

ANSWER:

For each metal combination measured in this experiment the voltage has the same magnitude but opposite signs when red-black leads of multimeter are switched.

This pattern could be explained because the electrochemical cells is formed by two half-cells that correspond to half-cell reactions of reduction and oxidation. Those half-reactions produce a potential due to electron flow generated by the reduced element (electron earning) and the oxidized element (electron loss). This potential (voltage) is specific for each cell because each half-reaction (oxidation and reduction) has a defined potential.

The metals used in each cells are called electrodes: the positive electrode is the cathode and the negative electrode is the anode. When the black-red wires of multimeter are connected to metals of the electrochemical cell, we can observe a positive sign or a negative sign.

• A positive potential sign in multimeter => red wire (positive terminal) is connected to cathode and the black wire (negative terminal) is connected to anode. This means that electron flow from the black wire to red wire is spontaneous.
• A negative potential sign in multimeter => red wire is connected to anode and the black wire is connected to cathode. This means that electron flow from the black wire to red wire is non-spontaneous.