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. Go < 0 for
Br2(l) + 2 Hg(l) ---> 2 Br-(aq) + Hg22+(aq).  

b. 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.

Attached file(s):

Question from chemistry.doc  View File