Cell Potentials

Question 1

What is a galvanic cell?

Answer 1

Like a battery - chemical to electrical

Question 2

What is an electrolytic cell?

Answer 2

Electrical to chemical energy

Question 3

What is the equilibrium cell potential?

Answer 3

Ecathode - Eanode

Question 4

What is the Nernst Equation used for?

Answer 4

Non-standard conditions when calculating cell potential

Question 5

What is the reaction quotient?

Answer 5

If the reaction is written as a reduction equation, a, b are on left, c, d are on right.

Q = Cc Dd / Aa Bb (square brackets around the capitals indicate the concentration of the species

Question 6

What is a Pourbaix diagram?

Answer 6

Potential pH diagrams that indicate regions of potential and pH where a metal will undergo or is protected from corrosion.

Question 7

What are the two non-corrosion regions on a Pourbaix diagram?

Answer 7

Passivation - stable oxide or hydroxide or salt is formed which coats the metal and prevents contact with the solution

Immunity - metal is in contact with solution but corrosion reaction is energetically impossible

Question 8

What are the 3 possible straight lines on a Pourbaix diagram?

Answer 8

Horizontal - Corresponds to potential and not pH - no H+ involved in reaction

Vertical - No redox reaction - no transfer of electrons - it is an acid/base reaction

Sloping lines - Potential is a function of pH - involves H+ and transfer of electrons

Question 9

Finish Pourbaix diagrams