Electrochemistry
Zn
ZnSO4(aq)
CuSO4(aq)
Zn
Cu
Electrochemistry
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Battery – uses the energy from a
redox reaction to produce an electric
current and do work.
Electrochemistry – the study of the
interchange of chemical and electrical
energy.
Electrochemistry
2 Types of electrochemical processes
1. The production of an electric current
from a chemical (redox) reaction –
battery, voltaic cell, galvanic cell.
2. The use of an electrical current to
produce a chemical change (redox
reaction). Call this electrolysis.
Electrochemistry
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How do we capture the energy?
Separate the oxidizing agent (electron
acceptor) from the reducing agent
(electron donor)
Requires the electron transfer to occur
through a wire or an electric motor!
Figure 18.1: Schematic for separating the
oxidizing and reducing agents in a redox
reaction.
Why is there
no flow of
electrons
here?
8H+ + MnO4- + 5e-  Mn2+ + 4H20 ; Fe2+  Fe3+ + e-
Figure 18.2: Electron
flow.
Build up of charges
would require large
amounts of energy
Solutions must
be connected
to allow ions
to flow
8H+ + MnO4- + 5e-  Mn2+ + 4H20 ; Fe2+  Fe3+ + e-
Figure 18.4: The salt bridge
contains a strong
electrolyte.
Figure 18.4: The porous
disk allows ion flow.
Electrochemistry
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Want to allow ions to flow but not mix
the solutions
Electrons flow in the wire from
reducing agent to oxidizing agent
Electrochemical battery
(galvanic cell)

A device powered by a redox reactions
where the oxidizing agent is separated
from the reducing agent so that the
electrons must travel through a wire
from reducing agent to oxidizing agent
Electrochemical battery
(galvanic cell)
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Reducing agent loses electrons so it is
oxidized
Electrode where oxidation occurs is
called the anode
Oxidizing agent gains electrons and is
reduced
Electrode where reduction occurs is
the cathode
Figure 18.5: Schematic of a battery.
Anode - electrode where oxidation occurs
Cathode – electrode where reduction occurs
Electron flow
anode to cathode
oxidation to reduction
Electrochemistry
Go back to first cell with Zn and Cu and draw
a voltaic cell. Label anode, cathode, and show
direction of e- flow. Write out the two half
reactions and then write out the complete
reaction.
Cu/Zn Voltaic Cell
Cu
Zn
SO42-
Zn2+
Cu2+
Zn2+
Cu2+ + 2e-  Cu Cathode/reduction
Zn  Zn2+ + 2eAnode/oxidation
Cu2+ + Zn  Zn2+ + Cu
Electrochemistry