When an aqueous concentrate solution of lithium chloride is electrolysed using inert electrodes:

(a) Cl₂ is liberated at the anode

(b) Li is deposited at the cathode

(c) As the current flows, pH of the solution around the cathode remains constant

(d) As the current flows, pH of the solution around the cathode increases

When you electrolyze an aqueous solution of lithium chloride (LiCl) using inert electrodes, several interesting reactions occur at both the anode and cathode. Let's break down the process and analyze each statement you've provided to determine which ones are accurate.

Electrolysis of Lithium Chloride Solution

During electrolysis, an electric current is passed through the solution, causing chemical reactions at the electrodes. In the case of lithium chloride, the solution dissociates into lithium ions (Li⁺) and chloride ions (Cl^-). The reactions at the electrodes can be understood as follows:

Reactions at the Anode

At the anode, oxidation occurs. The chloride ions (Cl^-) lose electrons to form chlorine gas (Cl₂):

• 2 Cl^- → Cl₂ + 2 e^-

This confirms that statement (a) is true: chlorine gas is indeed liberated at the anode.

Reactions at the Cathode

At the cathode, reduction takes place. The lithium ions (Li⁺) gain electrons to form lithium metal (Li):

• Li⁺ + e^- → Li

This means that statement (b) is also true: lithium is deposited at the cathode.

Impact on pH of the Solution

Now, let's consider the pH changes in the solution. As the electrolysis proceeds, water is also involved in the reactions. At the cathode, the reduction of water can occur, producing hydroxide ions (OH^-):

• 2 H₂O + 2 e^- → H₂ + 2 OH^-

The generation of hydroxide ions increases the concentration of OH^- in the solution, which leads to an increase in pH. Therefore, statement (d) is correct: as the current flows, the pH of the solution around the cathode increases.

On the other hand, statement (c) is incorrect. The pH does not remain constant; it actually rises due to the formation of hydroxide ions.

Summary of Findings

To summarize:

• (a) True: Cl₂ is liberated at the anode.
• (b) True: Li is deposited at the cathode.
• (c) False: The pH of the solution around the cathode does not remain constant.
• (d) True: The pH of the solution around the cathode increases.

This process illustrates the fascinating interplay of electrochemical reactions and their effects on the solution's properties. Understanding these reactions is crucial for applications in electrochemistry, such as battery technology and electroplating.