The pH of a 0.02 M solution of hydrochloric acid is

Options

A. `2.0`
B. `1.7`
C. `0.3`
D. `2.2`

Explanation

To find the pH of a 0.02 M solution of hydrochloric acid (HCl), follow these steps:

### Step 1: Understand the nature of HCl
Hydrochloric acid (HCl) is a strong acid, which means it completely ionizes in solution. This means that the concentration of hydrogen ions (H⁺) in the solution will be equal to the concentration of the HCl solution.

### Step 2: Determine the concentration of H⁺ ions
Since HCl completely dissociates in water, the concentration of H⁺ ions will be the same as the concentration of the HCl solution:
\[ [H^+] = [HCl] = 0.02 \, \text{M} \]

### Step 3: Calculate the pH
The pH is calculated using the formula:
\[ \text{pH} = -\log[H^+] \]
Substituting the concentration of H⁺ ions into the formula:
\[ \text{pH} = -\log(0.02) \]

### Step 4: Perform the logarithmic calculation
Using a calculator:
\[ \text{pH} = -\log(0.02) \approx 1.70 \]

### Conclusion
The pH of a 0.02 M solution of hydrochloric acid is approximately 1.70.

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