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    Electrochemical cells, Bonds, and Lattice

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    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
    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.

    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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    Solution Summary

    Answers questions form Electrochemical cells, half reactions, lead storage batteries, lattice, melting point, hydrogen bonds, bond angles etc.