ELECTROCHEMISTRY
What is Electrochemistry?

NaCl + AgBr

Na


+

CaCl2 
In which reaction to do elements change charges?
How could this happen?
Rxn 2  electrons transfer from 1 element to
another
What is Electrochemistry?


Branch of chemistry that deals with electricityrelated applications of oxidation-reduction
reactions (REDOX reactions)
REDOX (Reduction-Oxidation Reactions):
reactions in which elements undergo changes in
oxidation number as a result of electron
transfer
Definitions

What is Reduction?
 When
an atom or ion GAINS one or more electrons
Na+ + 1e-  Na
 The
charge of this atom/ion will be reduced
 This atom/ion also called the oxidizing agent
Definitions

What is Oxidation?
 When
an atom or ion LOSES one or more electrons
Cu  Cu2+ + 2 e The
charge of this atom/ion will increase
 This atom/ion also called the reducing agent
Identify oxidation and reduction

Must assign oxidation numbers.
 Always
assign the most electronegative element
first, with its typical charge.
 Pure elements have an oxidation number of zero.
Fe2O3 + CO  Fe + CO2
Identify oxidation and reduction
CO + I2O5  CO2 + I2
Reduced: ____________Oxidized: _____________
H2
+
O2

H2O
Reduced: ___________ Oxidized: ____________
Al
+
Fe2O3 
Al2O3
+ Fe
Reduced: ___________ Oxidized: ____________
Identify oxidation and reduction
S8
+
NO3¯ 
SO32- + NO
Reduced: ________ Oxidized: __________
Mn2+ +
BiO3¯ 
Bi3+
+
MnO4¯
Reduced: _________ Oxidized: ____________
Applications of Electrochemistry

Electroplating https://www.youtube.com/watch?v=ctL6Oc0STUU
 Layering
a metal of atoms over the surface of another
metal
Car bumpers
 Pennies


Metal processing
 Extracting
Al3+ ions from the soil and turning it into pure
Al metal

Batteries https://www.youtube.com/watch?v=ksxSOwA933M
 Converts
chemical energy to electrical energy using
electrochemical cells
Voltaic Cell
Voltaic Cell


use spontaneous
oxidation-reduction
reactions to convert
chemical energy into
electrical energy.
practical application:
batteries
Batteries