Introduction to Electrochemistry

Reorder metals. Place the ones that want to give away electrons first.

These metals are most reactive

• K

  (Potassium)

• Magnesium

  (Mg)

• Zn

  (Zinc)

• Cu

  (Copper)

• Au

  (Gold)

Which element(s) gain electrons in this reaction?

Cu²⁺(aq) +  Zn(s)  → Zn²⁺(aq) + Cu(s)

(Most reactive metals want to give away electrons like crazy!)

• Zinc

• Copper

• Both

• None

Which element(s) will be in solution after the reaction happens?

Cu²⁺(aq) +  Zn(s)  → Zn²⁺(aq) + Cu(s)

(Hint 1: the ions will be in solution)

(Hint 2: An ion is a charged atom)

• Zinc

• Copper

• Both

• None

 Cu²⁺(aq) + 2e^- → Cu(s)  has potential of 0.34V

What is the potential of   Cu(s) → Cu²⁺(aq) + 2e^-

Mathematical Equivalence

ON

Voltaic stack above is made of copper and zinc.    

Cu(s) → Cu²⁺(aq) + 2e^- has potential of -0.34V.

Zn²⁺(aq) + 2e^- → Zn(s) has potential of -0.76V.

What is the total potential of the cell?

Zn²⁺(aq) + 2e^- + Cu(s) → Cu²⁺(aq) + 2e^- + Zn(s)

Mathematical Equivalence

ON

We want to use Aluminum and Copper to generate electricity. Which metal will gain electrons?

• Aluminum

• Copper

Aluminum and Copper are placed together. The half reactions are:

Al³⁺+ 3 e⁻ -> Al(s) -1.66V

Cu⁺ + e^- -> Cu(s) 0.52V

What will be resulting voltage?

Hint: Aluminum gives away electrons. It goes from solid to solution. Copper gains electrons. It goes from solution to solid.

Mathematical Equivalence

ON

Copper and Aluminum wires are used for electrochemical cell. They are placed in copper sulfate solution (a source of copper ions). You found that the voltage is +2.18V. Will the reaction be spontaneous, will the cell work?

Hint: If the overall electric potential (voltage) is greater than 0, then the reaction is spontaneous.

• Spontaneous

• Non-spontaneous