CHEM 35

General Chemistry

Quiz #3

 

September 29, 2000

Name:       Key, Francis Scott           

 

  1. For the following reaction*:

 

          MnO4- + H2S ® Mn2+ + SO42- + 2H+

 

    1. What are the oxidation states for Mn, S, and H in this reaction (both in the reactants and in the products)?

 

REACTANTS                      PRODUCTS

Mn: x + 4(-2) = -1

X = +7     +2

 

          S:  2(+1) + x = 0             x + 4(-2) = -2

                  X = -2                       x = +6

 

          H:     +1                            +1

 

    1. Which compound undergoes oxidation and which compound undergoes reduction? Be sure to explain how you arrived at your answer!

 

Oxidation: loses electrons, incr. in oxidation #

S: -2 -> +6

 

Reduction: gains electrons, decr. in oxidation #

Mn: +7 -> +2

 

  1. Identify the Lewis acid and the Lewis base in the following reaction (don’t forget to explain how you arrived at your answer):

 

                      Ni2+ + 6H2O  ® Ni(H2O)62+

 

Lewis Base: electron pair donor -> the oxygen on water has two non-bonded electron pairs, making it a suitable donor

 

Lewis Acid: electron pair acceptor -> Ni2+ has the capacity to accept the electron pairs donated by the oxygens on water


* Yes, it is unbalanced – don’t worry about that . . . .