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Electrolysis

الكلية كلية العلوم للبنات     القسم قسم الكيمياء     المرحلة 3
أستاذ المادة حازم يحيى محمد علي الجبوري       23/11/2019 04:58:13
Electrolysis is the process of causing the nonspontaneous reaction to occur using the
external electrical source or the process of transforming the electrical energy into
chemical energy. An apparatus for carrying out electrolysis is called electrolytic cell.
The electrochemical principles underlying both galvanic cell and electrochemical cell are
the same. An electrolytic cell, like galvanic cell, also consists of two electrodes in a
molten salt or electrolyte solution that is connected to external battery or other voltage
source. The external battery serves as the electron pump, which draws electrons in at one
electrode (the positive electrode) and forcing them out at another (the negative electrode).
Here I have shown a simplified electrolytic cell utilizing the molten NaCl as an
electrolyte with two inert electrodes: In molten sodium chloride (NaCl), there are two ions, namely, cation Na+
and anion Cl-
.
At the anode, the oxidation of chloride ion takes place by depositing two electrons and
forming a pure chlorine gas. At the same time, the reduction of sodium ion takes place at
the cathode forming a pure sodium metal. The reactions at both electrodes are given
below:
Oxidation (anode): 2Cl-
(l) ? Cl2(g) + 2e-
E0
ox = -1.36 V
Reduction (cathode): 2Na+
(l) +2e- ? 2Na(l) E0
red = -2.71 V
Overall: 2Na+
(l) +2Cl-
(l) ? 2Na(l) + Cl2(g) E0
cell = - 4.07 V

It is important to note here is that pure sodium and chlorine gas are formed at cathode and
anode electrodes respectively.
The calculated E0
cell value indicates that this reaction is a nonspontaneous one and
requires an external electrical energy of equal to or greater than 4.07 V to carry out
reaction. Higher voltage than 4.07 may be necessary due to inefficiencies in electrolytic
process.
In the above electrolytic cell, pure sodium and pure chlorine gas are produced at the
electrodes. The question is, how much of these substances are formed?

المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .