pH of 1 M HCl is

Options

A. zero
B. `-2`
C. 7
D. 14

Answer

To find the pH of a 1 M HCl solution, we can follow these steps:

### Step 1: Understand the dissociation of HCl
HCl is a strong acid that completely dissociates in water. This means that when you have a 1 M solution of HCl, it will dissociate into H⁺ ions and Cl⁻ ions:
\[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \]

### Step 2: Determine the concentration of H⁺ ions
Since HCl dissociates completely, the concentration of H⁺ ions in a 1 M HCl solution is also 1 M:
\[ [\text{H}^+] = 1 \, \text{M} \]

### Step 3: Use the pH formula
The pH of a solution is calculated using the formula:
\[ \text{pH} = -\log[\text{H}^+] \]

### Step 4: Substitute the concentration of H⁺ ions into the pH formula
Now, we can substitute the concentration of H⁺ into the pH formula:
\[ \text{pH} = -\log(1) \]

### Step 5: Calculate the logarithm
The logarithm of 1 is 0:
\[ \log(1) = 0 \]

### Step 6: Final calculation of pH
Now substituting this value back into the pH equation:
\[ \text{pH} = -0 = 0 \]

### Conclusion
Thus, the pH of a 1 M HCl solution is:
\[ \text{pH} = 0 \]