Question

Which of the following reactions don't occur spontaneously and can be brought about only through electrolysis, assuming that all reactants and products are in their standard states?

(a) 2H2O(l)→2H2(g)+O2(g) [in 1 M H+(aq)]

(b) Zn(s)+Fe2+(aq)→Zn2+(aq)+Fe(s)

(c) 2Fe2+(aq)+I2(s)→2Fe3+(aq)+2I−(aq)

(d) Cu(s)+Sn4+(aq)→Cu2+(aq)+Sn2+(aq)

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All attempts used; correct answer displayed

Correct answer is a,c,d

Part B

For the reaction (a), what is the minimum voltage required?

Express your answer to three decimal places and include the appropriate units.

E∘cell =

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Part C

For the reaction (c), what is the minimum voltage required?

Express your answer to three decimal places and include the appropriate units.

E∘cell =

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Part D

For the reaction (d), what is the minimum voltage required?

Express your answer to three decimal places and include the appropriate units.

E∘cell =

Answer 1

Part A: Correct answer is a,c,d

(a) 2H2O(l)→2H2(g)+O2(g) [in 1 M H+(aq)]

(c) 2Fe2+(aq)+I2(s)→2Fe3+(aq)+2I−(aq)

(d) Cu(s)+Sn4+(aq)→Cu2+(aq)+Sn2+(aq)

∆E°(cell) = E°(cathode) -E° (anode)

Part B

For the reaction (a), 1.229 vis the minimum voltage required.

(a) 2H2O(l)→2H2(g)+O2(g) [in 1 M H+(aq)]

1.229 v

Part C

For the reaction (c), 0.236 V is the minimum voltage required.

Fe3+ + e- ---- > Fe2+ 0.770

I3- + 2 e- ----- > 3 I- 0.5338

2Fe2+(aq)+I2(s)→2Fe3+(aq)+2I−(aq)

0.236 V

Part D

For the reaction (d), 0.183 V is the minimum voltage required.

Cu2+ + 2 e- Cu 0.3402

Sn4+ + 2 e- Sn2+ 0.15

(d) Cu(s)+Sn4+(aq)→Cu2+(aq)+Sn2+(aq)

0.1902 V