To calculate the pH of a strong acid like hydrochloric acid (HCl), you can use the following formula:
\[ \text{pH} = -\log[\text{H}^+] \]
Since HCl is a strong acid, it dissociates completely in water:
\[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \]
This means that the concentration of hydrogen ions \([\text{H}^+]\) in a 0.2 M solution of HCl is also 0.2 M.
Now, substituting this into the formula:
\[ \text{pH} = -\log(0.2) \]
Using a calculator, you find:
\[ \text{pH} \approx 0.70 \]
Therefore, the pH of a 0.2 M HCl solution is approximately 0.70.
1 answer