Docsity
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Docsity AI
Docsity AI
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search for your university

Find the specific documents for your university's exams

Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

Electrolysis: Process, Factors, and Applications in Chemistry, Study notes of Chemistry

Kennesaw State University (KSU)Chemistry

An in-depth exploration of electrolysis, a chemical process that uses electric current to induce non-spontaneous reactions. Topics include the differences between electrolytic and voltaic cells, factors affecting electrolysis reactions, calculations using faraday's constant, and various applications such as electrorefining, electrosynthesis, and the chloro-alkali process.

Typology: Study notes

2021/2022

Uploaded on 09/12/2022

themask
themask ๐Ÿ‡บ๐Ÿ‡ธ

4.4

(17)

310 documents

1 / 4

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Electrolysis
Tabl e of Co ntent s
1. Electrolytic Cell vs Voltaic Cell
2. Factors Affecting Electrolysis Reactions
3. Calculations
4. Application
5. References
6. Problems
7. Answers
8. Contributors
The use of electric current to stimulate a non-spontaneous reaction. Electrolysis can be used to separate a substance
into its original components/elements and it was through this process that a number of elements have been
discovered and are still produced in today's industry. In Electrolysis, an electric current it sent through an electrolyte
and into solution in order to stimulate the flow of ions necessary to run an otherwise non-spontaneous reaction.
Processes involving electrolysis include: electro-refining, electro-synthesis, and the chloro-alkali process.
Electrolytic Cell vs Voltaic Cell
Example: When we electrolyze water by passing an electric current through it, we can separate it into hydrogen and
oxygen.
2H2O(l)โ†’2H2(g)+O2(g)
More information : The Electrolysis of Water
An electrolytic cell is essentially the non-spontaneous reaction's voltaic cell, (in fact if we reversed the flow of
electricity within a voltaic cell by exceeding a required voltage, we would create an electrolytic cell). Electrolytic cells
consist of two electrodes (one that acts as a cathode and one that acts as an anode), and an electrolyte. Unlike a
voltaic cell, reactions using electrolytic cells must be electrically induced and it's anode and cathode are reversed
(anode on the left, cathode one the right).
Voltaic
Electrolytic
Oxidation: X โ†’ X+ + e- (Negative Anode)
Y โ†’ Y+ + e- (Positive Anode)
Reduction: Y+ + e- โ†’ Y (Positive Cathode)
X+ + e- โ†’ X (Negative Cathode)
Overall: X + Y+โ†’ X+ + Y (G<0)
X+ + Y โ†’ X + Y+ (G>0)
This reaction is spontaneous and will release energy
This reaction is non-spontaneous and will absorb energy
pf3
pf4

Partial preview of the text

Download Electrolysis: Process, Factors, and Applications in Chemistry and more Study notes Chemistry in PDF only on Docsity!

Electrolysis

Table of Contents

  1. Electrolytic Cell vs Voltaic Cell
  2. Factors Affecting Electrolysis Reactions
  3. Calculations
  4. Application
  5. References
  6. Problems
  7. Answers
  8. Contributors

The use of electric current to stimulate a non-spontaneous reaction. Electrolysis can be used to separate a substance into its original components/elements and it was through this process that a number of elements have been discovered and are still produced in today's industry. In Electrolysis, an electric current it sent through an electrolyte and into solution in order to stimulate the flow of ions necessary to run an otherwise non-spontaneous reaction. Processes involving electrolysis include: electro-refining , electro-synthesis , and the chloro-alkali process.

Electrolytic Cell vs Voltaic Cell

Example: When we electrolyze water by passing an electric current through it, we can separate it into hydrogen and oxygen.

2 H 2 O ( l )โ†’ 2 H 2 ( g )+ O 2 ( g )

More information : The Electrolysis of Water

An electrolytic cell is essentially the non-spontaneous reaction's voltaic cell, (in fact if we reversed the flow of electricity within a voltaic cell by exceeding a required voltage, we would create an electrolytic cell). Electrolytic cells consist of two electrodes (one that acts as a cathode and one that acts as an anode), and an electrolyte. Unlike a voltaic cell, reactions using electrolytic cells must be electrically induced and it's anode and cathode are reversed (anode on the left, cathode one the right).

Voltaic Electrolytic Oxidation: X โ†’ X+^ + e-^ (Negative Anode) Y โ†’ Y+^ + e-^ (Positive Anode) Reduction: Y+^ + e-^ โ†’ Y (Positive Cathode) X+^ + e-^ โ†’ X (Negative Cathode) Overall: X + Y+โ†’ X+^ + Y (G<0) X+^ + Y โ†’ X + Y+^ (G>0) This reaction is spontaneous and will release energy This reaction is non-spontaneous and will absorb energy

Factors Affecting Electrolysis Reactions

  1. Overpotential- The generated voltage is significantly higher than expected. An overpotential may be necessary to overcome interactions taking place on the electrode itself (especially for gasses).
  2. Electrode type- An inert electrode acts as a surface for a reaction to occur on and is not involved in the chemical reaction whereas an active electrode becomes a part of the half reaction.
  3. Simultaneous electrode reactions- If two different pairs of half-reactions take place at once. Some half reactions should be eliminated in order to determine a single pair of half reactions best suited for the electrolysis to occur.
  4. The state of reactants- If reactants are in nonstandard states, the voltage of half cells may differ from that of the standard amount. In this case, the solution for the anode half cell may have a pH that is either higher or lower than the standard pH of 4 which may lead to a nonstandard voltage as well.

Calculations

Faraday's Constant -The amount of electric charge associated with one mole of electrons.

  1. Mercury Cell Process

Electrolysis of seawater in a mercury cell leads to the production of chlorine and sodium hydroxide at the same time. This method involves using mercury as the cathode and graphite as the anode.The mercury attracts either sodium or potassium cations and the mercury forms an amalgam with it. However when the amalgam is introduced to water it forms sodium hydroxide and hydrogen leaving the mercury to be reused later. The chlorine gas is left to form at the anode.

  1. Diaphragm Cell Process The diaphragm cell has Cl 2 being released from the anode section, while there is H 2 being released from the cathode section. If Cl 2 manages to mix with NaOH, the Cl turns into other products. Therefore the diaphragm cell has a bigger amount of NaCl,and a smaller amount of solution in the cathode in order for the NaCl to come in contact with the other solution gradually, while simultaneously preventing backflow of NaOH.
  2. Membrane Cell Process This process is more efficient than others as it does not use mercury and does not require a significant amount of energy. Contains a cation-exchange membrane which is usually made from flourocarbon polymer. This membrane allows hydrated cations to pass in between the anode and cathode compartments, but does not allow the backflow of the ions, Cl-^ and OH-. This allows the sodium hydroxide produced to have less contamination by chloride ions.

References

  1. Miller, Fredrick P.,McBrewster, John, Vandome, Agnes F. Cathode: Electrode, Electric current, Anode, Battery (electricity), Cathode bias, Electrolysis, Electrolytic cell, Electron. United States: Alphascript Publishing, 2009.
  2. Hale, Arthur J. The Applications of Electrolysis in Chemical Industry. New York:General Books LLC, 2010.
  3. Petrucci, Ralph H., Harwood, William S., Herring, F. G., and Madura Jeffrey D. General Chemistry: Principles and Modern Applications. 9th ed. Upper Saddle River: Pearson Education, Inc., 2007.
  4. Hoffman, Brittany; Mitchell, Elizabeth; Roulhac, Petra; Thomes, Marc; Stumpo, Vincent M. " Determination of the Fundamental Electronic Charge via the Electrolysis of Water ." J. Chem. Educ. 2000 77 95.

Contributors

๏‚ท Kimberly Song (UC Davis)

Source: http://chem wiki.ucdavis.edu/Analytical_Chem istry/Electrochem istry/Electrolytic_Cells/Electrolysis