What is the pH of 1 molar HCl?
Understand the Problem
The question is asking for the pH of a 1 molar solution of hydrochloric acid (HCl). Since HCl is a strong acid, it completely dissociates in water, and the pH can be calculated using the formula pH = -log[H+], where [H+] is the concentration of hydrogen ions. In this case, the concentration of hydrogen ions is equal to the molarity of the HCl solution, which is 1 M.
Answer
The pH of the 1 molar solution of hydrochloric acid (HCl) is 0.
Answer for screen readers
The pH of the 1 molar solution of hydrochloric acid (HCl) is 0.
Steps to Solve
- Identify the concentration of hydrogen ions
Since hydrochloric acid (HCl) is a strong acid, it completely dissociates in water. Therefore, the concentration of hydrogen ions, $[H^+]$, in a 1 molar solution of HCl is 1 M.
- Use the pH formula
To find the pH of the solution, we use the formula:
$$ pH = -\log[H^+] $$
Inserting the value for $[H^+]$:
$$ pH = -\log(1) $$
- Calculate the pH
Now we calculate:
Since the logarithm of 1 is 0 ($\log(1) = 0$), we have:
$$ pH = -0 $$
Thus:
$$ pH = 0 $$
The pH of the 1 molar solution of hydrochloric acid (HCl) is 0.
More Information
A pH of 0 indicates a very strong acidic solution. The pH scale ranges from 0 to 14, with lower values indicating stronger acids. A 1 M solution of HCl is one of the strongest acid concentrations commonly encountered in chemistry.
Tips
- Misunderstanding the dissociation of strong acids: Remember that strong acids like HCl fully dissociate in water, meaning the concentration of hydrogen ions equals the concentration of the acid.
- Forgetting to use the logarithm: Ensure to apply the pH formula correctly, which includes taking the negative logarithm of the hydrogen ion concentration.
