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Electrochemistry- Cathodes and Anodes

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(there are six procedures with the same questions for each procedure)

Procedure 1 LAB:

Beaker #1: 150 ml CuSO4
Beaker #2: 150 ml SnCl2
Salt Bridge connects the two beakers
electrode in CuSO4 is set to copper
electrode in SnCl2 is set to tin
volt meter reads .4761

Question:

1. Identify the cathode and anode in this system.

2. Use the table for Standard Reduction Potentials at 25 degrees C (half reaction table increasing strength as an oxidizing agent). How does teh calculated value compare to the experimentally obtained value?

3. What does the reduction potential of this cell say about the spontaneity of this redox reaction? Are products or reactants favored? How do you know?

Procedure 2 LAB:

Beaker #1 150 ml CuSO4
Beaker #2 150 ml AgNO3
Salt bridge connects the two
electrode for beaker #1 set to copper
electrode for beaker #2 set to silver
Volt meter reads -.4594

Questions

1. Identify the cathode and anode in this system.

2. Use the table for standard reduction potentials at 25 degrees C (half reaction table increasing strength as an oxidizing agent). How does the calculated value compare to the experimentally obtained value?

3. What does the reduction potential of this cell sy about the spontaneity of this redox reaction? Are products or reactants favored? How do you know?

LAB Procedure 3

Beaker #1 150 ml CuSO4
Beaker #2 150 ml ZnSO4
Salt Bridge
electrode CuSO4 set to copper
electrode ZnSO4 set to zinc
Volt meter reads 1.103

Questions

1. Identify the cathode and anode in this system.

2. Use table for standard reduction potentials at 25 degrees C (half reaction table increasing strength as an oxidizing agent). How does the calculated value compare to the experimentally obtained value?

3. What does the reduction potential of this cell say about the spontaneity of this redox reaction? Are products or reactants favored? How do you know?

Procedure 4 LAB

Beaker #1 150ml SnCl2
Beaker #2 150ml ZnSO4
Salt bridge
electrode SnCl2 set to tin
electrode ZnSO4 set to zinc
Volt meter reads .6269

Questions

1. Identify the cathode and anode in this system.

2. Use the table for standard reduction potentials at 25 degrees C (half reaction table increasing strength as an oxidizing agent). How does the calculated value compare to the experimentally obtained value?

3. What does the reduction potential of this cell say about the spontaneity of this redox reduction? Are products or reactants favored? How do you know?

Procedure 5 LAB

Beaker #1 150ml SnCl2
Beaker #2 150ml AgNO3
Salt Bridge
electrode SnCl2 set to tin
electrode AgNO3 set to silver
Volt meter reads -.9357

Questions

1. Identify the cathode and anode in this system.

2. Use the table for standard reduction potential at 25 degrees C (half reaction table increasing strength as an oxidizing agent). How does the calculated value compare to the experimentally obtained value?

3. What does the reduction potential of this cell say about the spontaneity of this redox reaction? Are the products or reactants favored? How do you know?

Procedure 6 LAB

Beaker #1 150ml ZnSO4
Beaker #2 150ml AgNO3
Salt bridge
electrode ZnSO4 set to zinc
electrode AgNO3 set to silver
Volt meter reads -1.562

Question

1. Identify the cathode and anode in this system.

2.Use the table for standard reduction potential at 25 degrees C (half reaction table increasing strength as an oxidizing agent). How does the calculated value compare to the experimentally obtained value?

3. What does the reduction potential of this cell say about the spontaneity of this redox reaction? Are products or reactants favored? How do you know?

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https://brainmass.com/chemistry/oxidation-reduction-and-electrochemistry/176480

Solution Preview

Lab 1
Look at your voltmeter reading to get an idea of which half reaction is oxidized and which is reduced.

1. Cathode (reduction): Copper
Anode (oxidation): Tin

2. From Standard Reductions Table in back of Chemistry book.
Cu2+ + 2e- -> Cu(s) E = 0.337 V
Sn(s) -> Sn2+ + 2e- E = 0.14 V

E(total) = 0.337 + 0.14 = 0.477 V

3. Spontaneity of a chemical reaction is determined by the overall cell potential Ecell. If Ecell>0, the reaction is spontaneous and if Ecell<0, the reaction will not be spontaneous. This can also be looked at in terms of the gibss free energy (G). If G<0, the reaction is spontaneous and if G>0, the reaction will not ...

Solution Summary

Cathodes and anodes in an electrochemical system are discussed. Redox reactions and the reduction of potential are found.

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See Also This Related BrainMass Solution

Electrochemical cells, half reactions, lead storage batteries, lattice, melting point, hydrogen bonds, bond angles,

Question 1 Consider the following electrochemical cell:
Cu(s) | CuSO4(aq) || KCl(aq) | Cl2(g) | C(graphite).
Identify the matching pairs below. (transferred from anode to cathode, produced at the cathode, oxidizing agent, does not lose nor gain mass, reducing agent, loses mass)

Cu metal
Cl2(g)
electrons
Cu2+ ions
chloride ions
C(graphite) electrode
Cu electrode

Question 2 (0.7 points)
What is the E°cell for the cell that forms from the following half reactions?
Fe3+(aq) + e- ---> Fe2+(aq)
Zn2+(aq) + 2e- ---> Zn(s)

a. -1.53 V

b. -0.01 V

c. ) 0.78 V

d. 0.01 V

e. 1.53 V

Question 3 (0.7 points)
Which one of the following statements is true?

a. Only lead storage batteries can be placed in series.

b. A lead storage battery's voltage output depends strongly on the temperature.

c. Metallic lead is reduced at the cathode of a lead storage battery.

d. A dry cell battery is not rechargeable.

e. A fuel cell does not require a continuous supply of reactants.

Question 4 (0.9 points)
Calculate the cell potential for the reaction
Zn(s) + 2 Cr+3(aq)[0.010 M] ---> 3 Zn+2(aq)[0.020 M] + 2 Cr(s)
given, Cr+3(aq) + 3e- ---> Cr(s) . . . . . . . Eo = -0.74 V
Zn+2(aq) + 2e- ---> Zn(s) . . . . . . .Eo = -0.76 V

a. +0.01 V

b. -0.01 V

c. + 0.03 V

d. -0.03 V

e. -0.02 V

Question 5 (1 point)
The following cell was observed to have an emf of 2.29 volts at 25.0oC :
Zn(s) | Zn2+(aq,0.112 M) || Cl-(aq) | Cl2(g; 0.472 atm) | Pt(s) .
Use tables of standard reduction potentials in Silberberg to calculate the concentration of chloride ion in the cathode compartment, [Cl-] / M . Your answer should be dimensionless (no units) and be given to 2 significant figures.
Scientific notation should be entered as 6.2e-3 for 6.2 x 10-3.
Answer

Question 6 (0.9 points)
Which of the following statements are FALSE?

a. &#61508;Go < 0 for
Br2(l) + 2 Hg(l) ---> 2 Br-(aq) + Hg22+(aq).

b. &#61508;Go < 0 for
NO3-(aq) + 4 H+(aq) + Au(s) ---> NO(g) + 2 H2O(l) + Au3+(aq).

c. The cell potential for
Co|Co2+(0.1 M)||Fe3+(0.5 M)|Fe2+(1.5 M)|Pt
is greater than 1.05 V.

d. The cell potential for
Co|Co2+(0.25 M)||Fe3+(0.5 M)|Fe2+(1.0 M)|Pt
is greater than 1.05 V.

e. The cell potential for
Cu|Cu2+(2.0 M)||Cl2(2.0 atm)|Cl-(2.0 M)|Pt
is less than 1.02 V.

Question 8 (0.9 points)
A certain metal crystallizes in a structure that has 4 atoms per unit cell, and the unit cell is a cube. How is the lattice described for this metal?

a. ) body centered cubic

b. ) simple cubic

c. ) face centered cubic

d. ) hexagonal

e. ) tetragonal

Question 9 (0.7 points)
Which has the highest melting point?

a. ) Na

b. ) Mg

c. ) W

d. ) Ba

e. ) they all exhibit the same melting point

Question 10 (0.8 points)
Which of the species listed below can form hydrogen bonds with water molecules?

a. Na+ ions

b. CH3OH (methanol)

c. C2H6 (ethane)

d. HCOOH (formic acid)

e. CCl4 (carbon tetrachloride)

Question 11 (0.8 points)
Which of the following has the smallest bond angles?

a. ) CO2

b. ) SO2

c. ) SO3

d. ) SO42-

Question 12 (0.8 points)
Select the false statements from the following:

a. XeF4 is tetrahedral.

b. CH2F2 is nonpolar.

c. The four bond moments of SiH4 add to zero.

d. The nitrite ion, NO2-, is linear.

e. The nitrate ion, NO3-, is AB3E.

Bonus questions:
1. Chlorine gas can oxidize zinc metal
a. Write half-reactions involved
b. Write the cell diagram for this process
c. Mark anode and cathode. Which reaction occurs at anode? Which at cathode?
2. In an experiment, chlorine is formed in reaction of potassium permanganate with concentrated hydrochloric acid. Write equation for the reaction; balance it showing all steps of balancing.

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