Electrochemistry

Question 1

Galvanic Cells

Answer 1

• Electrons always travel from anode to cathode
• E° of the cell will always be positive
• The free energy change and emf always have opposite signs

Cell diagram:

anode | anode sol’n || cathode sol’n | cathode

Question 2

Electrolytic Cells

Answer 2

Same as galvanic cells but external voltage is applied.

• Cell potential is negative
• Electrons flow in opposite directions
• Original cathode becomes anode, and vice versa

Question 3

-nFE° = change in free energy

Answer 3

If the electrical potential is positive, the reaction is spontaneous. If it is negative, the reaction is nonspontaneous.

Question 4

AN OX and a RED CAT

Answer 4

The ANode is the side of OXidation; REduction occurs at the CAThode

Question 5

Concentration Cell

Answer 5

Special type of galvanic cell, but the electrodes are chemically identical. The current is generated as a function of a concentration gradient.

• The EMF is zero when the concentrations are equal

Question 6

Rechargeable cell

Answer 6

Can function as both a galvanic and electrolytic cell

Question 7

Isoelectric focusing

Answer 7

A technique used to separate amino acids or polypeptides based on isoelectric points.

• Negatively charged (acidic) amino acids will be attracted to the anode
• Positively charged (basic) amino acids will be attracted to the cathode

Question 8

Nernst equation

Answer 8

E_cell = E^°_cell - (.0592/n)logQ

Question 9

Salt Bridge

Answer 9

Contains an electrolyte which contains ions that will not react with electrodes or with ions in solution. Exchanges antions and cations to balance, or dissipate, newly generated charges