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QUESTION

Please help me to answer these questions For the first ?

Please help me to answer these questions

For the first ? sent Ag/Cu cell = 0.402V,Cu/Zn= -0.912, Al/Cu =-0.410, Cu/Mg= -1.57

Report Sheet: Voltaic Cells

Part A: Voltaic Cells Results: In this part, we measure and rank the reduction potentials of selected half-cells.

Table I. Measured Cell Differences - Spontaneous Reaction Direction

Half-cell

electrode

Ered

relative

to Cu2+

(V)

Anode

half-cell

Cathode

half-cell

Overall spontaneous redox rxn between the half-cells.

(anode half-cell = oxidation, cathode half-cell = reduction)

Ecell

(V)

Ag

Pb

Zn

Al

Mg

1. Referring Table I, if you were to place the black probe of the voltmeter on the silver electrode and the red probe on the

Zinc electrode:

a) What voltage would the voltmeter read?

b) Which electrode would act as the anode?

c) Write the overall spontaneous redox reaction that would occur:

Use your Ered values relative to Cu to make a list of relative reduction potentials for the measured half-cells. Include Cu in

the list. List the most positive half-cell reduction potential at the top of Table II, the least positive on the bottom. Write the

corresponding REDUCTION half-rxn for each half-cell. Convert your half-cell voltages (relative to Cu2+) to voltages

relative to the standard hydrogen electrode. Finally, report the literature standard reduction potential for each metal.

Table II. Experimental Reduction Half-reaction Voltages.

Reduction half-reaction

Ehalf-rxn (V)

(measured in lab

relative to Cu2+)

Ehalf-rxn (V)

relative to the SHE

(add 0.34 V)

Literature

E ̊red (V)

2. Based on Table II:

a) What metal is the strongest reducing agent?

b) What ion is the strongest oxidizing agent?

3. For two of the metals, you should have observed that the voltage measurements were difficult to obtain because the

voltage reading was not stable. For these two metals, your results are likely to be relatively inaccurate. Identify the two

metals that behaved this way and explain clearly and completely explain why they do so. (Hint: Think about the ease

with which these two metals are oxidized, the reduction of water and what is formed on the surface of these metals when

immersed in water or exposed to the atmosphere.)

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