Redox reactions

Chapter 11 Assignment

Task 1 –Redox reactions

Determine if each reaction is an oxidation or reduction.

Ca²⁺_(aq)  +  2e^– ⇌ Ca_(s)

Fe_(s) ⇌ Fe²⁺_(aq) + 2e^–

Cu²⁺_(aq) + e^– ⇌ Cu⁺_(aq)

Na_(s) ⇌ Na⁺_(aq)  + e^–

Cr²⁺_(aq) ⇌ Cr³⁺_(aq)+ e^–

Task 2 –  Galvanic Cells

1. Calculate the standard cell potential produced by a galvanic cell consisting of the following half-cells. Which is anode and which is the cathode?
2. a) Na⁺_(aq) + e^– ⇌ Na_(s) E° = -2.71 V

Cu²⁺_(aq)  +  2e^– ⇌ Cu_(s)     E° = 0.34 V

ANODE:

CATHODE:

E° =

1. b) Al³⁺_(aq) + 3e^– ⇌ Al_(s) E° = -1.66 V

Fe²⁺_(aq)  +  2e^– ⇌ Fe_(s)      E° = -0.44 V

ANODE:

CATHODE:

E° =

2. Use half-reaction potential values from the PPT presentation or go to https://openstax.org/books/chemistry-atoms-first-2e/pages/16-3-electrode-and-cell-potentials and predict whether the following reactions are spontaneous or non-spontaneous in aqueous

1. d) Ca2+(aq) + 2 I-(aq) àCa(s) + I2(aq)

Reaction at ANODE:

Reaction at CATHODE:

E° =

Spontaneous or non-spontaneous?

1. d) 2 H+(aq) + 2 Br-(aq) àH2(g) + Br2(aq)

Reaction at ANODE:

Reaction at CATHODE:

E° =

Spontaneous or non-spontaneous?

1. e) Cr2+(aq) + Cu2+(aq)  à  Cr3+(aq)   + Cu+(aq)

Reaction at ANODE:

Reaction at CATHODE:

E° =

Spontaneous or non-spontaneous?

Task 3– Activity Series

Look at the following reactions and answer the questions below.

Al (s) + Pt⁺² à solid formed

Al (s) + Zn⁺² à solid formed

Pt (s) + Zn⁺² à no reaction

• Is Al more reactive than Pt?
• Is Al more reactive than Zn?
• Is Pt more reactive than Zn?
• Write the activity series in decreasing order of activity from most to least.

______________>_____________>____________

Task 4  –  Reactivity

1. Why do nail manufacturers coat iron nails (Fe) with zinc to form galvanized iron? – explain in relation to the activity series.

1. Why are water heaters attached to a magnesium rod? Explain the process and paste a link to your reference.

1. Why do ship hulls and propellers have sacrificial metals? Explain the process and paste a link to your reference.

1. During the rusting process (see reaction below), identify the oxidizing agent and the reducing agent.

4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃

1. When looking at the following video, how can you tell which electrode produces oxygen and which electrode produces hydrogen? https://www.youtube.com/watch?v=HQ9Fhd7P_HA

1. What is the biggest advantage of a lithium-ion battery over a Ni-Cad battery?