pH of the NaCl solution after electrolysis will

Options

A. increase
B. decrease
C. remain constant
D. can't be determined

Explanation

To determine the effect on the pH of a NaCl solution after electrolysis, we can follow these steps:

### Step 1: Understand the Electrolysis Process
During the electrolysis of a sodium chloride (NaCl) solution, two main reactions occur: one at the cathode and one at the anode.

### Step 2: Identify the Reactions
At the cathode (negative electrode), water is reduced, producing hydrogen gas (H₂) and hydroxide ions (OH⁻):
\[ 2H_2O + 2e^- \rightarrow H_2(g) + 2OH^-(aq) \]

At the anode (positive electrode), chloride ions (Cl⁻) are oxidized to produce chlorine gas (Cl₂):
\[ 2Cl^- \rightarrow Cl_2(g) + 2e^- \]

### Step 3: Write the Overall Reaction
Combining the two half-reactions, the overall reaction for the electrolysis of NaCl solution can be represented as:
\[ NaCl(aq) + H_2O(l) \rightarrow Na^+(aq) + OH^-(aq) + H_2(g) + \frac{1}{2}Cl_2(g) \]

### Step 4: Analyze the Effect on pH
The production of hydroxide ions (OH⁻) at the cathode increases the basicity of the solution. Since pH is a measure of the hydrogen ion concentration, an increase in hydroxide ions will result in a decrease in hydrogen ion concentration, leading to an increase in pH.

### Step 5: Conclusion
As a result of the electrolysis of NaCl solution, the pH of the solution will increase due to the formation of hydroxide ions.

### Final Answer
The pH of the NaCl solution after electrolysis will increase.

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