Page 91 - [B._MURPHY,_C._MURPHY,_B._HATHAWAY]_A_working_meth

Electrochemistry I: Galvanic Cells 75
given to you in an examination; what you must be familiar with is the
relative positions of the elements).
'Little Potty Sammy Met A Mad Zebra In Lovely Honolulu Causing
Strange Gazes'!

i.e. Little Lithium Li -3.09 V
Potty Potassium K
Sammy Sodium Na
Met Magnesium Mg
A Aluminium A1
Mad Manganese Mn
Zebra Zinc Zn
In Iron Fe
Lovely Lead Pb
Honolulu Hydrogen H 0.00 v
Causing Copper cu
Strange Silver Ag
Gazes Gold Au +1.69V

The Electrochemical Series can be summarised as follows.

Elements with large positive reduction potentials, E", are easy to
reduce and are good oxidising agents, e.g.
F2 + 2e + 2F- E" = 2.87 V
Elements with large negative reduction potentials, E", are diffi-
cult to reduce themselves, but are good reducing agents, e.g.
Na+ + e+Na E0=-2.71V
Species with low E" values reduce species with high E" values
and species with high E" values oxidise species with low E"
values, i.e. low reduces high and high oxidises low (HOL).
zqs) + CU2+(aq) -, CU(~) + Zn2+(,,).
E"(Zn2+, Zn) = -0.76 V; E"(Cu2+, Cu) = +0.34 V.

Reduction potentials vary in a complicated way throughout the
periodic table. Generally however, the most negative are found on the
left side of the table and the most positive are found on the right side.
~
The Electrochemical Series will be discussed in greater detail in
Chapter 7, with respect to electrolytic cells. In such cells, the position
of an element in the activity series will determine the appropriate
electrode half-cell reaction.