Galvanic cells

  • #1

Main Question or Discussion Point

In a galvanic cell is it the anions from the electrolyte which is attracted to the cathode or is it the anions produced from the anode dissolving which flow to the cathode??

Also it mentions that the charges increase in energy as they pass through the power supply and they decrease when they pass through the consumer. What exactly is a charge? Is it just an electron or is it a proton with electrons or what??
 

Answers and Replies

  • #2
Astronuc
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In a galvanic cell is it the anions from the electrolyte which is attracted to the cathode or is it the anions produced from the anode dissolving which flow to the cathode??
Both species of atoms can be involved depending on the construction of the cell, i.e. whether there is a single or dual electrolyte. However the reactions are dissolution (by oxidation), which occurs at the anode and precipitation (by reduction), which occurs at the cathode. Atoms dissolved from the anode will interact chemically with the electrolyte.

Also it mentions that the charges increase in energy as they pass through the power supply and they decrease when they pass through the consumer. What exactly is a charge? Is it just an electron or is it a proton with electrons or what??
The electrons are the charge carriers through a power supply. Is one thinking of an electrolytic cell in this case?

Electrons and protons have charge. Electrons are negatively charged, while protons (and the atomic nucleus which contains protons and neutrons) are positively charged. Keep in mind that electrons are 'small' with a mass of ~1/1835 of a proton, and so electrons are more mobile than protons or atoms.

These might help in understanding the phenomena involved.

http://en.wikipedia.org/wiki/Galvanic_cell

http://en.wikipedia.org/wiki/Electrolytic_cell

http://en.wikipedia.org/wiki/Electrochemical_cell

http://en.wikipedia.org/wiki/Alkaline_battery

http://en.wikipedia.org/wiki/Electrode_potential
http://en.wikipedia.org/wiki/Nernst_equation


http://chemistry.about.com/library/weekly/aa082003a.htm


http://www.mpoweruk.com/chemistries.htm (some good graphics here)


http://www.science.uwaterloo.ca/~cchieh/cact/c123/battery.html (some bad links on this page)
http://www.science.uwaterloo.ca/~cchieh/cact/c123/emf.html

This is helpful - The Galvanic Cell and the p-n Junction
http://www.rose-hulman.edu/~moloney/BoisePNjunctionOperation.html


Electrochemical and Electrolytic cells
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/electrochem.html
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/electrolyt.html

Electrochemistry concepts
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html

Thermodynamic potentials
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thepot.html

Oxidation/Reduction concepts
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/redoxcon.html


CZ batteries
http://www.eveready.com/pdfs/ever_cz_appman.pdf [Broken]

Zn-MnO2 batteries
http://www.eveready.com/pdfs/ever_alkcylin_appman.pdf [Broken]
 
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  • #3
That pretty much explains it. Thanks alot. One things still unclear to me though.

When the dissolution takes place at the anode do hydrogen ions break off and leave electrons attached to the anode followed by the hydrogen ions precipitating on the cathode? If so does that mean the anode gradually erodes and the cathode gradually expands?

Also is the electrode potential the electronegativity difference of the two electrodes which determines which one will be the reductant(anode) and which will be the oxidant(cathode)?
 

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