# chemistry

if you're given a chart of half cell potentials (reduction potentials), how can you figure out which metals produce the highest voltage?

For ex.
Silver (Ag) with zinc (Zn)

would you say that pb and zn produce the highest voltage because they result in the biggest difference? even though pb and zn have the largest negative voltage.

Silver (Ag) with copper (Cu)

i think it would be ag and cu for the same reason as above.

1. 👍
2. 👎
3. 👁
1. similarly, from the chart, how can you determine which combinations of metals (if used to create an electrochemical cell) produce the largest voltage?

1. 👍
2. 👎
2. do i have to see which of the two metals are bring reduced and oxidized to determine the voltage?

1. 👍
2. 👎
3. This is usually a trying subject for students and I'll answer the last post and ignore the others. I think that will be the best for all of these questions since all of them are related. So, "do i have to see which of the two metals are bring reduced and oxidized to determine the voltage?".

Yes. As an example, do this. Suppose you have a cell consisting of Cu and Zn, how do you know which is the anode and which the cathode?
Reduction potential for Cu is + 0.337
Reduction potential for Zn is -0.763 or
Cu^2+ + 2e ==> Cu Eo = +0.337
Zn^2+ + 2e ==> Zn Eo = -0.763
I think the texts say to choose the one with the largest negative voltage and reverse that equation. That would be
Zn ==> Zn^2+ + 2e Eox = +0.763 and combine with Cu reduction
Cu^2+ + 2e ==> Cu Ered = 0.337 then add the Eox + Ered
----------------------------------------------------
Zn + Cu^2+ + 2e ==> Zn^2+ + Cu + 2e Etotal = 1.100 volts. Of course in the final equation the 2e on each side cancel. How do you know if this cell is possible? Because you get a POSITIVE voltage. A positive voltage tells you any reaction you've set up will react as written. A negative value will tell you the reaction will not go as written but will go in the opposite reaction.
Which electrode is the anode and which the cathode? The definition of anode is "oxidation occurs at the anode". Which of the two are oxidized. Since oxidation is the loss of electrons the Zn metal is oxidized so Zn is the anode anode and Cu is the cathode.
In practice I have my own method but it's no better than what the texts teach. I KNOW that the metal with the largest oxidation potential will be the anode so I mentally reverse those numbers. That tells me Zn will be the anode and Cu the cathode so I KNOW to write Zn as an oxidation equation and to write Cu as the reduction equation, then I add the two. Hope this helps. Another way is just go with luck; i.e., choose EITHER one, reverse it, leave the other equation alone, then add the two voltages (remember to change the sign of the one you reverse). If the cell is negative you reversed the wrong one so do the opposite. If the cell is + you made a lucky choice.

1. 👍
2. 👎
👤
DrBob222

## Similar Questions

1. ### chemistry

Given these standard reduction potentials at 25oC: Cr3+ + e- -> Cr2+ (E1^o = -0.407V) Cr2+ + 2e- -> Cr(s) (E2^o = -0.913V) Determine the standard reduction potential at 25oC for the half-reaction equation: Cr3+ + 3e- -> Cr(s) This

2. ### chem

Q: Calculate ℰ° values for the following cells. Which reactions are spontaneous as written (under standard conditions)? Balance the equations. Standard reduction potentials are found in the Standard Reduction Potentials table.

3. ### Chemistry

A cell is set up with copper and lead electrodes in contact with CuSO4(aq) and Pb(NO3)2(aq), respectively, at 25˚C. The standard reduction potentials are: Pb2+ + 2e- --> Pb E˚=-0.13 V Cu2+ + 2e- --> Cu E˚=+.34 V If sulfuric

4. ### Chemistry

Given the following half-reactions and associated standard reduction potentials: AuBr−4(aq)+3e−→Au(s)+4Br−(aq) E∘red=−0.858V Eu3+(aq)+e−→Eu2+(aq) E∘red=−0.43V IO−(aq)+H2O(l)+2e−→I−(aq)+2OH−(aq)

1. ### Chemistry need help

using standard potentials given in the appendices calculate the standard cell potentials and the equilibrium constants for the following reactions. Zn(s)+( Fe^2+(aq)) ---> (Zn^2+(aq))+ Fe(s) If anyone can show work, then I can do

2. ### Chemistry

The cell diagram for the lead-acid cell that is used in automobile and truck batteries is Pb(s) l PbSO4 (s) l H2SO4 (aq) l PbO2(s), PbSO4(s) l Pb (s) where the comma between PbO2 (s) and PbSO4 (s) denotes a heterogeneous mixture

3. ### Chem

Calculate the standard cell potential given the following standard reduction potentials: Al3++3e−→Al;E∘=−1.66 V Fe2++2e−→Fe;E∘=−0.440 V

4. ### Chemistry

Constants The following values may be useful when solving this tutorial. Constant Value E∘Cu 0.337 V E∘Fe -0.440 V R 8.314 J⋅mol−1⋅K−1 F 96,485 C/mol T 298 K Part A In the activity, click on the E∘cell and Keq

1. ### chemistry

Based on the half-reactions and their respective standard reduction potentials below, what is the standard cell potential for the reaction that is expected to occur? Fe3+(aq) + e- → Fe2+(aq) 0.77 V Sn4+(aq) + 2 e- → Sn2+(aq)

2. ### Chemistry

Calculate the cell potential for the following reaction as written at 25.00 °C, given that [Zn2 ] = 0.842 M and [Ni2 ] = 0.0100 M. Standard reduction potentials can be found here. reaction: Zn(s)+Ni^2+(aq)--->Zn^2+(aq)+Ni(s)

3. ### Electrochemistry

In lab, we did an experiment with electrochemical cells with solutions of ZnSO4, CuSO4, Al2(SO4)3 and MgSO4 and their respective metal electrodes. There are a couple of post-lab questions that I'm not sure about: (1) Summarize

4. ### Chemistry

calculate cell potential at 25C for: 3Fe3+(aq) + AL(s)= 3Fe2+(aq)+ Al3+ (aq) if Fe3+ = 0.300 M, Fe2+ = 0.150M Al3+ = 0.300M. The standard reduction potentials are as follows: Fe3+ (aq) + e- = Fe2+ (aq) Al3+ (aq) + 3e-=Al (s) Eo =