Calculate the pH of following solutions.
`0.1N HCl`

Answer

To calculate the pH of a 0.1N HCl solution, follow these steps:

### Step 1: Understand the nature of HCl
HCl is a strong acid that completely dissociates in water. This means that when HCl is dissolved, it breaks down into H⁺ ions and Cl⁻ ions.

### Step 2: Determine the dissociation
The dissociation of HCl can be represented as:
\[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \]

Since HCl dissociates completely, the concentration of H⁺ ions produced will be equal to the concentration of the HCl solution.

### Step 3: Relate normality to molarity
For strong acids like HCl, the normality (N) is equal to the molarity (M) when the n-factor is 1 (since it donates one H⁺ ion per molecule). Therefore:
\[ \text{Molarity of HCl} = \text{Normality of HCl} = 0.1N = 0.1M \]

### Step 4: Calculate the concentration of H⁺ ions
From the previous step, we know that the concentration of H⁺ ions in the solution is:
\[ [\text{H}^+] = 0.1M \]

### Step 5: Calculate the pH
The pH is calculated using the formula:
\[ \text{pH} = -\log[\text{H}^+] \]
Substituting the concentration of H⁺ ions:
\[ \text{pH} = -\log(0.1) \]

### Step 6: Simplify the logarithm
Using properties of logarithms:
\[ \text{pH} = -\log(10^{-1}) \]
This simplifies to:
\[ \text{pH} = -(-1) \cdot \log(10) \]
Since \(\log(10) = 1\):
\[ \text{pH} = 1 \]

### Conclusion
The pH of the 0.1N HCl solution is **1**.

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