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1. What are the oxidation states of sulfur and fluorine, respectively, in the mo

ID: 961931 • Letter: 1

Question

1. What are the oxidation states of sulfur and fluorine, respectively, in the molecule, SF6?

2. Which reaction and statement correctly describes the electro-chemical cell shown and what voltage will be produced?

a. 2Al3+ + 3Pb+2 --> 2Al + 3Pb

b. 2Al3+ + 3Pb --> 3Pb2+ + 2Al

c. 2Al + 3Pb+2 --> 2Al3+ + 3Pb

d. 2Al + 3Pb --> 2Al3+ + 3Pb+2

a. e-‘s flow from the Al anode to the Pd cathode and nitrate ions diffuse into the Pb/Pb+2 solution.

b. e-‘s flow from the Pd cathode to the Al anode and nitrate ions diffuse into the Pb/Pb+2 solution.

c. e-‘s flow from the Al anode to the Pd cathode and nitrate ions diffuse into the Al/Al+3 solution.

d. e-‘s flow from the Pd cathode to the Al anode and nitrate ions diffuse into the Al/Al+3 solution.

a.   1.79 V      

b 1.53 V                         

c. -1.53 V              

d. -1.79 V              

e. 3.06 V

3. A product–favored electrochemical reaction has:

a. ?G° = 0, E° = 0, and K >> 1

b. ?G° < 0, E° > 0, and K > 1

c. ?G° > 0, E° < 0, and K < 1

d. ?G° > 0, E° < 0, and K > 1

4. An electrochemical cell based on the following reaction has a cell voltage, E°, of 2.12 V. Which change could make the cell voltage greater than 2.12 V?

Zn(s) + Cl2(g, 1 atm) Zn2+(aq, 1 M) + 2Cl¯(aq, 1 M)

a. add more Zn(s)

b. add more Cl¯(aq) ions
c. decrease the concentration of Zn2+(aq) ions
d. decrease the partial pressure of Cl2

e. ?G° < 0, E° = 0, and K >> 1

Explanation / Answer

1) sulfur ------> +6

    fluorine -------> -1

2)

correct answer : c.) 2Al + 3Pb+2 --> 2Al3+ + 3Pb

3)

answer : c. e-‘s flow from the Al anode to the Pd cathode and nitrate ions diffuse into the Al/Al+3 solution.

4)

Eo = E cathode - E anode

     = -0.13 - (-1.66)

     = 1.53 V

answer : b ) 1.53 V

5)

answer : b. G° < 0, E° > 0, and K > 1

6)

answer : c. decrease the concentration of Zn2+(aq) ions