Rajasthan BoardEnglish MediumSTD 12 ScienceChemistryElectrochemistry3 Marks
Question
Explain types of Electrodes with examples
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Answer
$(1)$ Active electrode :
$\rightarrow$ The active electrodes of metal are like $\ce{Zn, Ni, Cu, Ag}$ etc.
$\rightarrow$ Atoms of this kind of electrode undergo oxidation or reduced.
$\begin{array}{l} \ce{Zn \rightarrow Zn ^{2+}+2 e ^{-}} \text {(oxidation) } \\ \ce{Cu ^2++2 e ^{-} \rightarrow Cu} \text { (reduction) }\end{array}$
$(2)$ Inert electrode :
$\rightarrow$ Sometimes metals like platinum or gold are used as inert electrodes.
They do not participate in the reaction but provide their surface for oxidation or reduction reactions and for the conduction of electrons.
$\rightarrow$ For example, $Pt$ is used in the following half cells:
Hydrogen electrode : $\ce{Pt ( s )\left| H _2(g)\right| H ^{+}( aq )}$
with half $-$ cell reaction: $\ce{H ^{+}( aq )+ e ^{-} \rightarrow \frac{1}{2} H _2(g)}$
Bromine electrode : $\ce{Pt ( s )\left| Br _2( aq )\right| Br ^{-}( aq )}$
with half-cell reaction : $\ce{\frac{1}{2} Br _2( aq )+ e ^{-} \rightarrow Br ^{-}( aq )}$
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