What are different types of Reversible Electrodes? | Electrochemistry | Physical Chemistry
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Q.3 What are different types
Q.3 What are different types of Reversible Electrodes?
Ans.
The reversible cells are having electrodes are known as reversible electrodes. The reversible electrodes are of following types:
1. Metal - Metal ion Electrode: These electrodes are constructed by dipping any metal plate in its salt solution. It is the simplest type of electrode. In general, it is represented as { M }/{ { M }^{ +n } }. When this electrode is in LHE i.e. oxidation takes place, the reaction is M longrightarrow { M }^{ +n } + n{ e }^{ - }qquad qquad (Oxidation) e.g. Zn|{ Zn }^{ +2 }(aq)qquad qquad Zn longrightarrow { Zn }^{ +2 } + 2{ e }^{ - } Cu|Cu^{ +2 }(aq)qquad qquad Cu longrightarrow { Cu }^{ +2 } + 2{ e }^{ - } Al|Al^{ +3 }(aq)qquad qquad Al longrightarrow { Al }^{ +3 } + 3{ e }^{ - } Sn|Sn^{ +2 }(aq)qquad qquad Sn longrightarrow { Sn }^{ +2 } + 2{ e }^{ - } In this case the value of electrode potential depends on activity of metal ions.
2. Metal Sparingly Soluble Salt Electrode: In this case the metal and its sparingly soluble salt is in contact with the electrolyte which contains same anion. e.g. Ag, AgCl(s) C{ l }^{ - }qquad qquad Ag + C{ l }^{ - } longrightarrow AgCl(s) + { e }^{ - } Hg, Hg2Cl2(s) C{ l }^{ - }qquad qquad Hg + C{ l }^{ - } longrightarrow 1/2Hg2Cl2(s) + { e }^{ - } The potential value of this electrode also depends on the activity of ions (C{ l }^{ - }).
3. Gas electrode: There are several types of glass electrodes like Hydrogen Gas electrode, Chlorine Gas electrode Oxygen Gas electrode etc. In case of Hydrogen Gas electrode, H2 gas is bubbled through H+ ion solution e.g. HCl and for electrical contact we insert Platinum (Pt) wire which is the inert metal in electrochemistry. Hydrogen gas electrode on paper is written as Pt, H2|H+(aq) for oxidation, the reaction is 1/2 H2 rightleftarrows H+ +e- The potential of this electrode depends on the pressure of hydrogen gas and the activity of H+ ions.
4. Metal-Insoluble Oxide of Metal electrode: The electrode is obtained when metal and its insoluble oxide is in contact with OH- ions. e.g. Fe, FeO(s)|OH- (aq)qquad qquad Fe + 2OH- rightleftarrows FeO (s) + H2O + 2e- Sb, Sb2O3(s)|OH- (aq)qquad qquad 2Sb + 3OH- rightleftarrows 1/2Sb2O3 + 3/2H2O + 3e- Pt, Mn2O3(s), MnO2|OH- (aq)qquad qquad Mn2O3 + 2OH- rightleftarrows 2MnO2 (s) + H2O + 2e-
5. Redox electrode: When two different oxidation state of same element are present in the same solution and if we insert a Pt wire for electrical contact redox electrode s formed. and potential developed across the Pt wire is known as Redox electrode potential. e.g. Pt, Fe+2, Fe+3qquad qquad Fe+2 rightleftarrows Fe+3 + e- Pt, Sn+2, Sn+4qquad qquad Sn+2 rightleftarrows Sn+4 + 2e- In this case the electrode potential depends on the ratio of the activity of ions in the oxidation and reduction state of metal.
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Ans.
The reversible cells are having electrodes are known as reversible electrodes. The reversible electrodes are of following types:
1. Metal - Metal ion Electrode: These electrodes are constructed by dipping any metal plate in its salt solution. It is the simplest type of electrode. In general, it is represented as { M }/{ { M }^{ +n } }. When this electrode is in LHE i.e. oxidation takes place, the reaction is M longrightarrow { M }^{ +n } + n{ e }^{ - }qquad qquad (Oxidation) e.g. Zn|{ Zn }^{ +2 }(aq)qquad qquad Zn longrightarrow { Zn }^{ +2 } + 2{ e }^{ - } Cu|Cu^{ +2 }(aq)qquad qquad Cu longrightarrow { Cu }^{ +2 } + 2{ e }^{ - } Al|Al^{ +3 }(aq)qquad qquad Al longrightarrow { Al }^{ +3 } + 3{ e }^{ - } Sn|Sn^{ +2 }(aq)qquad qquad Sn longrightarrow { Sn }^{ +2 } + 2{ e }^{ - } In this case the value of electrode potential depends on activity of metal ions.
2. Metal Sparingly Soluble Salt Electrode: In this case the metal and its sparingly soluble salt is in contact with the electrolyte which contains same anion. e.g. Ag, AgCl(s) C{ l }^{ - }qquad qquad Ag + C{ l }^{ - } longrightarrow AgCl(s) + { e }^{ - } Hg, Hg2Cl2(s) C{ l }^{ - }qquad qquad Hg + C{ l }^{ - } longrightarrow 1/2Hg2Cl2(s) + { e }^{ - } The potential value of this electrode also depends on the activity of ions (C{ l }^{ - }).
3. Gas electrode: There are several types of glass electrodes like Hydrogen Gas electrode, Chlorine Gas electrode Oxygen Gas electrode etc. In case of Hydrogen Gas electrode, H2 gas is bubbled through H+ ion solution e.g. HCl and for electrical contact we insert Platinum (Pt) wire which is the inert metal in electrochemistry. Hydrogen gas electrode on paper is written as Pt, H2|H+(aq) for oxidation, the reaction is 1/2 H2 rightleftarrows H+ +e- The potential of this electrode depends on the pressure of hydrogen gas and the activity of H+ ions.
4. Metal-Insoluble Oxide of Metal electrode: The electrode is obtained when metal and its insoluble oxide is in contact with OH- ions. e.g. Fe, FeO(s)|OH- (aq)qquad qquad Fe + 2OH- rightleftarrows FeO (s) + H2O + 2e- Sb, Sb2O3(s)|OH- (aq)qquad qquad 2Sb + 3OH- rightleftarrows 1/2Sb2O3 + 3/2H2O + 3e- Pt, Mn2O3(s), MnO2|OH- (aq)qquad qquad Mn2O3 + 2OH- rightleftarrows 2MnO2 (s) + H2O + 2e-
5. Redox electrode: When two different oxidation state of same element are present in the same solution and if we insert a Pt wire for electrical contact redox electrode s formed. and potential developed across the Pt wire is known as Redox electrode potential. e.g. Pt, Fe+2, Fe+3qquad qquad Fe+2 rightleftarrows Fe+3 + e- Pt, Sn+2, Sn+4qquad qquad Sn+2 rightleftarrows Sn+4 + 2e- In this case the electrode potential depends on the ratio of the activity of ions in the oxidation and reduction state of metal.
For Details Visit
http://cepekmedia.co.nf
http://cepek.hol.es/
http://edmerls.66Ghz.com/
http://edmerls.tk/
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