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प्रश्न
How will the pH of brine (aq. \[\ce{NaCl}\] solution) be affected when it is electrolysed?
उत्तर
\[\ce{NaCl (aq) -> Na^{+} (aq) + Cl^{-} (aq)}\]
Cathode: \[\ce{H2O(l) + e^{-} -> 1/2 H2(g) + OH^{-} (aq)}\]
Anode: \[\ce{Cl^{-} (aq) -> 1/2 Cl2(g) + e^{-}}\]
Overall reaction: \[\ce{NaCl(aq) + H2O(l) -> NaOH(aq) + H2(g) + Cl2(g)}\]
\[\ce{NaOH}\] is a strong base, they turn the brine solution basic and pH will increase.
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Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half-reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half-cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If \[\ce{E^0_{cell}}\] is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as Cu2+. This was first formulated by Faraday in the form of laws of electrolysis.
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