Témbongkeun sumber pikeun Éléktrolisis

Dina widang [[kimia]] jeung manufaktur, '''éléktrolisis''' nujul ka métodeu misahkeun [[unsur kimia|unsur-unsur]] jeung [[sanyawa kimia|sanyawaan]] nu [[beungkeut kimia|kabeungkeut sacara kimia]] ku cara diasupan [[arus listrik]]. [[Sanyawa ionik]] dileyurkeun dina hiji [[pelarut]], atawa dilééhkeun ku [[panas]],antukna [[ion]]na aya dina cairan. Arus listrik dialirkeun antara sapasang [[éléktroda]] [[inert]] nu dikeueum dina cairanana. Unggal éléktroda narik ion-ion anu [[muatan listrik|muatanana]] sabalikna. Ion nu muatanana positip ([[kation]]) kabetot ku éléktroda négatip ([[katoda]]), sedengkeun ion nu muatanana négatip ([[anion]]) kabetot ku éléktroda [[positip]] ([[anoda]])<ref>Science Probe 10, 1996, p 234</ref>. [[Énérgi]] nu dipikabutuh pikeun misahkeun ion-ionna antukna ngagunduk di éléktroda papasanganana asalna tina listrik. Hasil tina ieu prosés nyaéta kaserep/kabeungkeut atawa dileupaskeunana [[éléktron]] ku ion-ion ngabentuk unsur atawa sanyawa anu dipikahayang.

[[Oksidasi]] anion bisa lumangsung dina anoda, sedengkeun di katoda bisa lumangsung [[réduksi]] kation. Conto oksidasi kation di anoda:
:<math>\mathrm{Fe^{2+}_{aq} \longrightarrow  \ Fe^{3+}_{aq} +  \ e^- }</math> .

Bisa ogé anion diréduksi di katoda:

:<math>\mathrm{Fe(CN)_6^{3-} + \ e^-  \longrightarrow  \ Fe(CN)_6^{4-} }</math> .

[[Molekul]] nétral bisa ogé robah dina éta dua éléktroda. Conto:

[[Gambar:P-Benzochinon.svg]] <math>\mathrm{+ \ 2 e^- + \ 2 H^+   \longrightarrow  \  }</math> [[Gambar:Hydrochinon2.svg]]

Jumlah énérgi listrik anu kudu ditambahkeun sarua jeung parobahan [[énérgi bébas Gibbs]] réaksina ditambah kaleungitan dina sistemna. <!--The losses can (in theory) be arbitrarily close to zero, so the maximum [[thermodynamics|thermodynamic]] efficiency equals the [[enthalpy]] change divided by the free energy change of the reaction. In most cases, the electric input is larger than the enthalpy change of the reaction, so some energy is released in the form of heat. In some cases, for instance, in the electrolysis of [[steam]] into hydrogen and oxygen at high temperature, the opposite is true. Heat is absorbed from the surroundings, and the [[heating value]] of the produced hydrogen is higher than the electric input. (It is worth noting that the maximum theoretic efficiency of a [[fuel cell]] is the inverse of that of electrolysis. It is, thus, impossible to create a [[perpetual motion]] machine by combining the two processes. See [[water fuel cell]] for an example of such an attempt.)

The following technologies are related to electrolysis:
* [[Electrochemical cell]]s, including the hydrogen [[fuel cell]], use the reverse of this process.
* [[Gel electrophoresis]] is an electrolysis wherein the solvent is a gel: It is used to separate substances, such as [[DNA]] strands, based on their electrical charge.

==Electrolysis of water==
[[Image:Hoffman voltameter.jpg|thumb|300px|Hoffman electrolysis apparatus used in electrolysis of water]]
{{main|Electrolysis of water}}

One important use of electrolysis of water is to produce hydrogen.
:2H<sub>2</sub>O<sub>(l)</sub> → 2H<sub>2(g)</sub> + O<sub>2(g)</sub>

This has been suggested as a way of shifting society toward using hydrogen as an [[energy carrier]] for powering electric motors and internal combustion engines. (''See [[hydrogen economy]].'')

Electrolysis of water can be observed by passing [[direct current]] from a battery or other DC power supply through a cup of water (in practice a saltwater solution increases the reaction intensity making it easier to observe). Using [[platinum]] electrodes, hydrogen gas will be seen to bubble up at the [[cathode]], and oxygen will bubble at the [[anode]]. If other metals are used as the anode, there is a chance that the oxygen will react with the anode instead of being released as a gas. For example, using iron electrodes in a sodium chloride solution electrolyte, iron oxide will be produced at the anode, which will react to form iron hydroxide. When producing large quantities of hydrogen, this can significantly contaminate the electrolytic cell - which is why iron is not used for commercial electrolysis.

The [[energy efficiency]] of water electrolysis varies widely. The efficiency is a measure of what fraction of electrical energy used is actually contained within the hydrogen. Some of the electrical energy is converted to heat, a useless by-product. Some reports quote efficiencies between 50% and 70%[http://www.hyweb.de/Knowledge/w-i-energiew-eng3.html] This efficiency is based on the Lower Heating Value of Hydrogen. The Lower Heating Value of Hydrogen is thermal energy released when Hydrogen is combusted. This does not represent the total amount of energy within the Hydrogen, hence the efficiency is lower than a more strict definition. Other reports quote the theoretical maximum efficiency of electrolysis. The theoretical maximum efficiency is between 80% and 94%.[http://bellona.org/filearchive/fil_Hydrogen_6-2002.pdf]. The theoretical maximum considers the total amount of energy absorbed by both the hydrogen and oxygen. These values refer only to the efficiency of converting electrical energy into hydrogen's chemical energy. The energy lost in generating the electricity is not included. For instance, when considering a [[nuclear power plant|power plant]] that converts the heat of nuclear reactions into hydrogen via electrolysis, the total efficiency is more like 25%–40%.[http://www.uic.com.au/nip73.htm]

About four percent of hydrogen gas produced worldwide is created by electrolysis, and normally used onsite. Hydrogen is used for the creation of ammonia for fertilizer via the [[Haber process]], and converting heavy petroleum sources to lighter fractions via [[hydrocracking]]. There is some speculation about future development of hydrogen as an energy carrier.

== Experimenters ==
Scientific pioneers of electrolysis included:
* [[Humphry Davy]]
* [[Michael Faraday]]
* [[Paul Heroult|Paul Héroult]]
* [[Svante Arrhenius]]
*[[Adolph Wilhelm Hermann Kolbe]]
* [[William Nicholson]]
* [[Joseph Louis Gay-Lussac]]
* [[Alexander von Humboldt]]

More recently, electrolysis of [[heavy water]] was performed by Fleischmann and Pons in [[Fleischmann-Pons experiment|their famous experiment]], allegedly resulting in anomalous heat generation and the controversial claim of [[cold fusion]].

==Faraday's laws of electrolysis==
{{main|Faraday's laws of electrolysis}}

===First law of electrolysis===

In [[1832]], [[Michael Faraday]] reported that the quantity of elements separated by passing an electrical current through a  molten or dissolved [[salt]] is proportional to the quantity of electric charge passed through the circuit. This became the basis of the first law of electrolysis:

<math>m = k \cdot q</math>

===Second law of electrolysis===

Faraday also discovered that the [[mass]] of the resulting separated elements is directly proportional to the [[atomic mass]]es of the elements when an appropriate integral divisor is applied. This provided strong evidence that discrete particles of matter exist as parts of the atoms of elements.

== Industrial uses ==
*Production of [[aluminium]], [[lithium]], [[sodium]], [[potassium]]
*Production of [[hydrogen]] for [[hydrogen car]]s and [[fuel cell]]s;  [[high-temperature electrolysis]] is also used for this
*[[Coulometry|Coulometric]] techniques can be used to determine the amount of matter transformed during electrolysis by measuring the amount of electricity required to perform the electrolysis
*Production of [[chlorine]] and [[sodium hydroxide]]
*Production of [[Sodium chlorate|sodium]] and [[potassium chlorate]]
*Production of perfluorinated organic compounds such as [[trifluoroacetic acid]]

Electrolysis has many other uses:
*[[Electrometallurgy]] is the process of reduction of metals from metallic compounds to obtain the pure form of metal using electrolysis. For example, sodium hydroxide in its molten form is separated by electrolysis into sodium and oxygen, both of which have important chemical uses. (Water is produced at the same time.)
*[[Anodization]] is an electrolytic process that makes the surface of metals resistant to [[corrosion]]. For example, ships are saved from being corroded by oxygen in the water by this process. The process is also used to decorate surfaces.
*A [[Battery (electricity)|battery]] works by the reverse process to electrolysis. [[Humphry Davy]] found that lithium acts as an electrolyte and provides electrical energy.
*Production of [[oxygen]] for [[spacecraft]] and [[nuclear submarines]]. 
*[[Electroplating]] is used in layering metals to fortify them. Electroplating is used in many industries for functional or decorative purposes, as in vehicle bodies and nickel coins.
*Production of hydrogen for fuel, using a cheap source of electrical energy.
*Electrolytic Etching of metal surfaces like tools or knives with a permanent mark or logo.
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== Baca ogé ==
* [[Hukum éléktrolisis Faraday]]
* [[Konstanta Faraday]]
* [[Éfisiénsi Faraday]]

== Rujukan ==
* Wikipédia édisi basa Inggris. ''[[:en:Electrolysis|Electrolysis]]''. Dibuka 26 Péb. 2007.

== Tumbu kaluar ==
* [http://www.youtube.com/watch?v=aK6cuypqD8M A video explaining the process of electrolysis and its application to cars]

{{elektrolisis}}

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