University of Phoenix

CHM 151

June 3, 2020

CHM/151: General Chemistry II

Week 5 Exercise

1)Balance the following in acidic solution:

 

1. H₂O₂ + Sn²⁺ ? H₂O+Sn⁴⁺

 

 

2. PbO₂+Hg?Hg₂²⁺+Pb²⁺

 

 

3.  

7

Al+Cr₂O ²⁻ ?Al³⁺+Cr³⁺

 

 

 

2. Balance the following in basic solution:

 

1.  

3                                             2                                                4

SO ²⁻(aq) + Cu(OH) (s) ? SO ²⁻(aq) + Cu(OH)(s)

 

 

2. O₂(g) + Mn(OH)₂(s) ? MnO₂(s)

 

 

3.  

3                          2

NO ⁻(aq) + H (g) ? NO(g)

 

 

4.  

4                                                3                                   4

Al(s) + CrO ²⁻(aq) ? Al(OH) (s) + Cr(OH) ⁻(aq)

 

 

 

3. Balance the following reactions and write the reactions using cell notation. Ignore any inert electrodes, as they are never part of the half-reactions.

 

1. Al(s) + Zr⁴⁺(aq) ? Al³⁺(aq) + Zr(s)

 

 

 

2.  

3

Ag⁺(aq) + NO(g) ? Ag(s) + NO ⁻(aq) (acidic solution)

 

 

 

3.  

3                                                                                                  2

SiO ²⁻(aq) + Mg(s) ? Si(s) + Mg(OH) (s) (basic solution)

 

 

 

 

3                                    2                                       4

d) ClO ⁻(aq) + MnO (s) ? Cl⁻(aq) + MnO ⁻(aq) (basic solution)

 

 

 

 

4. Determine the overall reaction and its standard cell potential at 25 °C for the reaction involving the galvanic cell made from a half-cell consisting of a silver electrode in 1 M silver nitrate solution and a half- cell consisting of a zinc electrode in 1 M zinc nitrate. Is the reaction spontaneous at standard conditions?

 

 

 

 

5. Consider a battery made from one half-cell that consists of a copper electrode in 1 M CuSO4 solution and another half-cell that consists of a lead electrode in 1 M Pb(NO3)2 solution.

 

1. What are the reactions at the anode, cathode, and the overall reaction?

 

2. What is the standard cell potential for the battery?

 

 

3. Most devices designed to use dry-cell batteries can operate between 1.0 and 1.5 V. Could this cell be used to make a battery that could replace a dry-cell battery? Why or why not.

 

 

4. Suppose sulfuric acid is added to the half-cell with the lead electrode and some PbSO4(s) forms. Would the cell potential increase, decrease, or remain the same?

 

 

 

 

6. How long would it take to reduce 1 mole of each of the following ions using the current indicated? Assume the voltage is sufficient to perform the reduction.

 

(a) Al3+, 1.234 A

 

 

(b) Ca2+, 22.2 A

 

 

(c) Cr5+, 37.45 A

 

 

(d) Au3+, 3.57 A