What is the pH of 0.01 M HCl?
Understand the Problem
The question is asking for the pH of a 0.01 M hydrochloric acid (HCl) solution. To find the pH, we first recognize that HCl is a strong acid and dissociates completely in solution. Since the concentration of HCl is 0.01 M, the concentration of hydrogen ions (H+) in the solution is also 0.01 M. The pH can be calculated using the formula pH = -log[H+].
Answer
The pH of the solution is $2$.
Answer for screen readers
The pH of the 0.01 M hydrochloric acid solution is 2.
Steps to Solve
- Identify the concentration of H+ ions
Since HCl is a strong acid and dissociates completely in solution, the concentration of hydrogen ions, $[H^+]$, is the same as the concentration of the HCl solution. Therefore, $$ [H^+] = 0.01 , M $$
- Use the pH formula
To calculate the pH, use the formula: $$ \text{pH} = -\log[H^+] $$
- Substitute the value of [H+] into the formula
Now, substitute $[H^+] = 0.01$ M into the pH formula: $$ \text{pH} = -\log(0.01) $$
- Calculate the pH
Using a calculator, we find: $$ \text{pH} = -\log(0.01) = -(-2) = 2 $$
The pH of the 0.01 M hydrochloric acid solution is 2.
More Information
The pH scale ranges from 0 to 14, where 7 is neutral. A pH below 7 indicates an acidic solution, and a pH of 2 signifies a relatively strong acid like hydrochloric acid.
Tips
- Forgetting to use the negative log: Sometimes students might overlook the negative sign in the pH formula, leading to incorrect pH values.
- Confusing molarity with pH: It's essential to remember that pH is a logarithmic measure of hydrogen ion concentration, not a direct representation of molarity.
