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Anode and Cathode confusion?

W

WAYNEL

Jan 1, 1970
0
Can any one give a good explanation that is not so confusion concerning
the anode and cathode, relating to rechargable batteries and cells.


At the cathode of a cell you get a reduction and at the anode you get
oxidation.
Electrons flow into cathode of the cell and thus produce a high
alkiline around the electrode, OH-.
Although on a Porbaix diagram the most negative side has a H+?

In electronics the cathode is negative and the anode in positive and
electrons travel from negtive to positive therefore the positive
(anode), when charging, will connect to the to the cathode of the
battery and cathode to anode of a battery???

Cheers

WayneL
 
C

Charles Schuler

Jan 1, 1970
0
WAYNEL said:
Can any one give a good explanation that is not so confusion concerning
the anode and cathode, relating to rechargable batteries and cells.


At the cathode of a cell you get a reduction and at the anode you get
oxidation.
Electrons flow into cathode of the cell and thus produce a high
alkiline around the electrode, OH-.
Although on a Porbaix diagram the most negative side has a H+?

In electronics the cathode is negative and the anode in positive and
electrons travel from negtive to positive therefore the positive
(anode), when charging, will connect to the to the cathode of the
battery and cathode to anode of a battery???

Electron flow is normally (forget zeners) from cathode to anode and
conventional current flow is opposite.

Diodes used as rectifiers used to have the cathode marked with a + symbol to
denote the positive end of the load circuit.

To turn on a diode (forget zeners) make the anode positive with respect to
the cathode.
 
W

WAYNEL

Jan 1, 1970
0
Charles said:
Electron flow is normally (forget zeners) from cathode to anode and
conventional current flow is opposite.

Diodes used as rectifiers used to have the cathode marked with a + symbol to
denote the positive end of the load circuit.

To turn on a diode (forget zeners) make the anode positive with respect to
the cathode.

Several hours of searching revieled a good explanation which furthers
what the Green book
http://www.iupac.org/publications/books/gbook/green_book_2ed.pdf
says.
A chemistry nomenclature
http://www.ktf-split.hr/glossary/en_s.php?def=cathode

States.

cathode

Cathode is a negative electrode of an electrolytic cell to which
positively charged ions (cations) migrate when a current is passed as
in electroplating baths.

In a primary or secondary cell (battery or accumulator) the cathode is
the electrode that spontaneously becomes negative during discharge, and
form which therefore electrons emerge.

In vacuum electronic devices electrons are emitted by the cathode and
flow to the anode.



WayneL
 
J

John O'Flaherty

Jan 1, 1970
0
WAYNEL said:
Can any one give a good explanation that is not so confusion concerning
the anode and cathode, relating to rechargable batteries and cells.


At the cathode of a cell you get a reduction and at the anode you get
oxidation.
Electrons flow into cathode of the cell and thus produce a high
alkiline around the electrode, OH-.
Although on a Porbaix diagram the most negative side has a H+?

In electronics the cathode is negative and the anode in positive and
electrons travel from negtive to positive therefore the positive
(anode), when charging, will connect to the to the cathode of the
battery and cathode to anode of a battery???

Merriam-Webster online has this definition for cathode:
1 : the electrode of an electrochemical cell at which reduction occurs:
a : the negative terminal of an electrolytic cell b : the positive
terminal of a galvanic cell
2 : the electron-emitting electrode of an electron tube; broadly : the
negative electrode of a diode

The definition for anode is the mirror image of this.
Galvanic cells are batteries, and electrolytic cells are loads.
Electrical diodes are loads and the terminals are named like those of
electrolytic cells.
 
B

Bob Masta

Jan 1, 1970
0
Several hours of searching revieled a good explanation which furthers
what the Green book
http://www.iupac.org/publications/books/gbook/green_book_2ed.pdf
says.
A chemistry nomenclature
http://www.ktf-split.hr/glossary/en_s.php?def=cathode

States.

cathode

Cathode is a negative electrode of an electrolytic cell to which
positively charged ions (cations) migrate when a current is passed as
in electroplating baths.

In a primary or secondary cell (battery or accumulator) the cathode is
the electrode that spontaneously becomes negative during discharge, and
form which therefore electrons emerge.

In vacuum electronic devices electrons are emitted by the cathode and
flow to the anode.

In chemistry class (back when there were only 4 elements)
the mnemonic that worked for me was that an "anion" was
"A Negative ION."

Hope this helps!



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
 
C

Charles Jean

Jan 1, 1970
0
Electron flow is normally (forget zeners) from cathode to anode and
conventional current flow is opposite.

Diodes used as rectifiers used to have the cathode marked with a + symbol to
denote the positive end of the load circuit.

To turn on a diode (forget zeners) make the anode positive with respect to
the cathode.
___

In electrolysis situations, I usually remember polarities by:

RED CAT
REDuction is the process occurring at the CAThode.
Therefore, oxidation must be the process occurring at the anode.

LEO GER
Substances Losing Electrons are Oxidized. Substances Gaining
Electrons are Reduced.

By knowing the two mnemonics, RED CAT and LEO GER you've got it all.

If you took two carbon rods and stuck them into a copper chloride
solution, you could predict which one would produce the chlorine gas
and which one would have copper plated on it:

Cu+2 + 2e- ---> 2Cu
copper has GAINed electrons. GER. REDuction has occurred. This
must be the CAThode. Copper will be plated here when electrons are
supplied from a battery's electron supply side or (-) pole.

2Cl- ---> Cl2 + 2e-
chlorine has Lost Electrons. LEO. Oxidation has occurred. This
must be the Anode. Chlorine gas will be generated here when connected
to the battery's electron deficient side or (+) pole.
 
B

Bob Masta

Jan 1, 1970
0
___

In electrolysis situations, I usually remember polarities by:

RED CAT
REDuction is the process occurring at the CAThode.
Therefore, oxidation must be the process occurring at the anode.

LEO GER
Substances Losing Electrons are Oxidized. Substances Gaining
Electrons are Reduced.

The mnemonic we learned for that is "LEO the lion roars, GER"

Best regards,




Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
 
The following is taken from the "Electrochemistry Dictionary"
http://electrochem.cwru.edu/ed/dict.htm

rechargeable battery
A battery in which the chemical reaction system providing the
electrical current is easily "chemically" reversible. After
discharging, it can be recharged by applying an electrical current to
its terminals. Some batteries can be recharged hundreds to thousands
times. See, e.g. the lead-acid battery. Also called "secondary"
battery, and "accumulator." Contrast with non-rechargeable battery.

It operates as a galvanic cell during discharge and as an electrolytic
cell during charge. As a consequence, the anode is the negative
electrode during discharge, while it is the positive electrode during
charge; at the same time, the cathode is the positive electrode during
discharge, while it is the negative electrode during charge. This can
create a confusing situation, and it is preferable to refer to the
electrodes of a rechargeable battery as "positive" and "negative,"
because this designation is independent of the operational mode.
Unfortunately, this nomenclature is not always followed. Often the
"negative" electrode is designated as anode and the "positive"
electrode is designated as cathode. This naming convention is a
carry-over from the convention of the non-rechargeable battery.


Good luck: ZN
 
J

jasen

Jan 1, 1970
0
On Wed, 03 Jan 2007 18:25:36 GMT, Charles Jean

The mnemonic we learned for that is "LEO the lion roars, GER"

I find OIL RIG more connvenient:
Oxidation Is Loss, Reduction Is Gain.

Bye.
Jasen
 
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