Answers - Electrochemistry 2

Arkansas State University
Department of Chemistry
and Physics

Answers

Electrochemistry 2

1. Write the cell diagram and calculate the E^o for the Zn/ Zn⁺² and Ca/Ca⁺² half-cells.
E^o= 2.11 V
cell diagram:
Ca (s) l Ca⁺² (aq, 1M) l KCl (sat'd) l Zn⁺² (aq, 1 M) l Zn (s)

2. a) Will I^- react with Br₂? Yes

b) Will Ni⁺² react with Br₂? No

c) Will Ni react with Br₂? Yes

Will Co⁺² react with Br₂ to give Co⁺³? No, reacts with Co⁺² to give Co (s)

3. Rank the following ions from strongest to weakest oxidizing agents:

E^o , V

Ag⁺ strongest + 0.80

Pb⁺² - 0.13

Al⁺³ - 1.66

Sr⁺² - 2.89

Li⁺ weakest - 3.05

4. Calculate DG^o for Cu⁺²/Cu and Mn⁺²/Mn half-cells. Is this reaction spontaneous?
E^o = 1.52 V; DG^o = - 293360 J or - 293.4 kJ; yes
5. Calculate DG for Ni⁺²/Ni and Fe⁺²/Fe half-cells if the [Ni⁺²] = 0.25 M and the [Fe⁺²] = 0.50 M.
E^o = 0.19 V; E = 0.181 V; DG = - 34956 J or - 35.0 kJ
6. Determine the DG for the Al⁺³/Al and Ni⁺²/Ni half-cells.if the [Al⁺³] = 0.50 M and the [Ni⁺²] = 0.25 M.
E^o = 1.41 V; E = 1.398 V; DG = - 809442 J or - 809.4 kJ
7. Is the reaction below spontaneous? no Calculate the E^o. E^o = - 0.47 V

Pb⁺² + Cu ------> Pb + Cu⁺²

2.	a) Will I^- react with Br₂?	Yes
	b) Will Ni⁺² react with Br₂?	No
	c) Will Ni react with Br₂?	Yes
	Will Co⁺² react with Br₂ to give Co⁺³?	No, reacts with Co⁺² to give Co (s)

		E^o , V
Ag⁺	strongest	+ 0.80
Pb⁺²		- 0.13
Al⁺³		- 1.66
Sr⁺²		- 2.89
Li⁺	weakest	- 3.05