 |
 |
1 of 16 |  |
 |
 |
P-1
EXPERIMENT P: ELECTROLYSIS AND THE SPONTANEITY OF
REDOX REACTIONS
OBJECTIVES
In this experiment you will electrolyze a dilute solution of sulfuric acid using a copper anode and an inert
nichrome (nickel/chromium alloy) cathode. You will determine the charge passed and the extent of a chemical
reaction. With this information you will determine the value of the Faraday Constant. You will also investigate
a number of simple redox reactions by making qualitative observations.
THEORETICAL CONSIDERATIONS
During an oxidation-reduction (redox) reaction, electrons are transferred. In an electrolytic cell, electrical
energy is used to drive a nonspontaneous redox reaction (electrolysis). Electrolytic processes follow laws first
proposed by Michael Faraday. These laws are able to quantify the chemical change that occurs within an
electrolytic cell, provided that the amount of charge passing through the cell is known.
Useful Relations
1.
Electric current (I) is measured in amperes and is defined as the flow of charge
(in coulombs) per second, therefore,
I = Q/t
where I is current in amperes (A), Q is charge in coulombs (C), and t is time in seconds.
2.
A coulomb of charge (C) is defined as the charge on 6.2415 x 10
18
electrons. The charge on one
mole of electrons (6.0221 x 10
23
electrons) is called the Faraday (F). A simple calculation will show
that the charge on one mole of electrons is 96485 C or 1 Faraday.
3.
Ohm's Law relates current (I) to voltage (V) and resistance (R) as follows:
V = I
R
where V is in volts, I is in amperes (A), and R is in ohms.
