1. Electrochemistry
Kenneth E. Schnobrich

2. Electrochemistry
Every element and ion has the potential to lose electrons as well as gain them - we can make use of these
differences in potential to lose and gain in the design of an ELECTROCHEMICAL CELL.
DEFINING TERMS:
OXIDATION - the loss of electrons by a species
REDUCTION - the gain of electrons by a species
OXIDIZING AGENT - the substance that undergoes
Reduction
REDUCING AGENT - the substance that undergoes
Oxidation

3. Electrochemistry DEFINING TERMS (cont.):
HALF-CELL - the container in which an oxidation or a reduction reaction occurs
SALT BRIDGE - allows a connection between the two half-cells and helps to maintain charge balance in the cell
ELECTRODE - a substance that serves as either the
Oxidizing or Reducing agent
VOLTMETER - a device that allows us to measure the voltage generated by a particular combination of half-cells

4. Electrochemistry
Which way will the electrons flow??

5. CHART “J” Na Mg Al Zn Fe Sn Pb H2 Cu Just a Sample Greater
Tendency to
Lose electrons
Better Reducing
Agent
List was taken from a version of the NYS Tables for Chemistry

6. VOLTAIC CELL

7. Zn0 + Cu+2 -> Cu0 + Zn+2 Ecell = +1.10v
Zn0 -> Zn e v
Cu e- -> Cu v
Zn0 + Cu+2 -> Cu0 + Zn Ecell = +1.10v e- e- e- e- e- e- e- e- e- e- e- e- e- e- e-
Oxidation - +
Reduction e-
KNO3 e-
Anode
Cathode
NO3- K+
Mass decrease
Mass increase

8. Chemical Reaction (REDOX) ------> Energy
SHORT-HAND NOTATION
Zn0|Zn+2||Cu0|Cu+2
Chemical Reaction (REDOX) > Energy

9. Mg|Mg+2||Ni0|Ni+2 What do we know: Mg is the anode (- electrode)
Ni is the cathode (+ electrode)
Mg is oxidized Mg0 -> Mg+2
Ni+2 is reduced Ni e- -> Ni0
Mg electrode decreases in mass
Ni electrode increases in mass
K+ moves toward Ni cell / NO3- moves toward Mg cell

10. Ecell CALCULATION Mg0 -> Mg+2 + 2e- Ni+2 + 2e- -> Ni0 +2.37v
Mg0 + Ni+2 -> Mg+2 Ni v

11. WHERE WILL A REDOX Rx OCCUR??
Using Table J
WHERE WILL A REDOX Rx OCCUR??
Al0
Ag0
Cu0
Al0
Mg+2
Cu+2
Ag+1
Fe+2

12. ELECTROLYTIC CELL
Energy ---> Chemical Reaction (REDOX)