Electrochemical Cells

Question 1

Do electrochemical cells usually undergo spontaneous or non-spontaneous reactions?

Answer 1

Spontaneous

Question 2

Where does oxidation and reduction occur in electrochemical cells?

Answer 2

Oxidation occurs at the anode and reduction occurs at the cathode

Question 3

How do you calculate E°?

Answer 3

E°cell = E°red - E°oxid

Question 4

How is a galvanic cell reaction carried out?

Answer 4

There are two half cell reactions that are carried out as separate half cells and are connected by a salt bridge

Question 5

What is a typical half cell?

Answer 5

It is made out of a metal rod in contact with an aqueous solution of metal ions, where the metal rod and metal ions are the components of a redox couple.

Question 6

What is a redox couple?

Answer 6

A pair of metals taking part in a redox reaction

Question 7

What is the purpose of the salt bridge?

Answer 7

It allows the flow of ions so that the charge in each half cell remains balanced

Question 8

Where do electrons flow in galvanic cells?

Answer 8

Through the external circuit

Question 9

What is the activity series?

Answer 9

Li → K → Na → Ca → Mg → Al → Zn → Fe → Sn → Pb → Cu → Ag

Question 10

Sum up an electrochemical cell

Answer 10

• Made up of two half cells (oxid and red)
• No outside source of electrons or energy, the cells produce the energy themselves
• A salt bridge (usually made of absorbent paper dipped in an ionic solid) allows the conduction of electrons between the two half cells
• The half cells undergoing reduction is easily identified by the reduction potential value (E°red - the rate at which electrons are gained by the oxidant). Usually the half cell with the higher E° is reduced.
• Cell notations are the representation of the electrochemical cell. Reduction is usually on the right.
• Reaction is always spontaneous (positive V)
• To make it non-spontaneous, you can reverse the half cells and the reduction half cell will become the oxidation half cell and vice versa.