Name: Electrolysis of Molten Ionic Compounds
Uploaded: 2019-07-19
Duration: 4 min 4 s
Description: Electrolysis is the process of decomposing ionic substances (breaking down) into simpler substances when an electric current is passed through them. Have a look at the process in this video.

Question

Write electrode reactions for the electrolysis of aqueous

NaCl

.

Accepted Answer

The electrolysis of aqueous solution of $NaCl$ with ptanium electrodes gives $H_{2}$ at the cathode and ${Cl}_{2}$ gas at the anode can be explained as follows:

Sodium chloride and water ionise as follows:

$NaCl (aq) \to {Na}^{+} (aq) + {Cl}^{-} (aq)$

$H_{2} O ⇌ H^{+} (aq) + {OH}^{-} (aq)$

Probable reactions at the cathode are:

${Na}^{+} (aq) + e^{-} \to Na (s) E_{Red}^{o} = - 2.71 V$

$2 H_{2} O (l) + 2 e^{-} \to H_{2} (g) + 2 {OH}^{-} (aq) E_{Red}^{o} = - 0.83 V$

Since the standard reduction potential of water is greater than the standard reduction potential of sodium. Therefore, water reduces at cathode and releases hydrogen gas.

Probable reactions at the anode are:

$2 {Cl}^{-} (aq) \to {Cl}_{2} (g) + 2 e^{-}, E_{ox}^{0} = - 1.36 V$

$H_{2} O (l) \to \frac{1}{2} O_{2} (g) + 2 H^{+} (aq) + 2 e^{-}, E_{ox}^{0} = - 1.23 V$

Since the standard oxidation potential of water and chloride ion is nearly same. The water needs greater voltage for oxidation of $O_{2}$ than that needs for oxidation of ${Cl}^{-}$ ions to ${Cl}_{2}$ . Therefore, ${Cl}_{2}$ release at anode.

Write electrode reactions for the electrolysis of aqueous $NaCl$ .

Important Questions on Electrochemistry

Learn and Prepare for any exam you want !

Write electrode reactions for the electrolysis of aqueous NaCl.

Important Questions on Electrochemistry

Learn and Prepare for any exam you want !

Write electrode reactions for the electrolysis of aqueous $NaCl$ .