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 electricity- related 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