Calculate pH of 4.41 M HCl Water Solution

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To calculate the pH of a 4.41 M HCl solution, the formula pH = -log[H+] can be applied, leading to a negative pH value, which is valid for strong acids at high concentrations. Such a high molarity is possible, as concentrated hydrochloric acid typically has a molarity around 10 M. The negative pH indicates a significant hydronium ion concentration, but the behavior of pH in highly concentrated solutions can be complicated due to ionic strength effects. Therefore, while the calculation is straightforward, the interpretation of pH in these scenarios requires consideration of additional factors. Understanding these complexities is essential for accurate pH assessments in concentrated acid solutions.
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Homework Statement



Hello everybody,
How can I calculate pH value of 4.41 M HCl water solution? Is it possible for such a solution to exist?

Thank you very much for your help,
CroSinus

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The Attempt at a Solution


When I try to find - log 4.41 I get a negative value. I do not know how to interpret my result.
 
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CroSinus said:
When I try to find - log 4.41 I get a negative value. I do not know how to interpret my result.
What is the definition of pH?
 
You can have a negative pH, though it is certainly wrong in your case and corresponds to > 1M strong acid.
 
epenguin said:
You can have a negative pH, though it is certainly wrong in your case and corresponds to > 1M strong acid.
Are you trying to tell me that a water solution with such a high molarity (4.41 M) is not possible?

Thank you very much,
CroSinus​
 
Bystander said:
What is the definition of pH?
I think I used an adequate definition formula for pH:
pH = - log (H+). Since HCl is a strong acid I assumed that c(HCl) = c(H+).

Thank you very much for your help,
Cro​
 
I’m sorry I must have misread your post. Your assumption is OK and the pH should be negative.
 
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CroSinus said:
pH = - log (H+). Since HCl is a strong acid I assumed that c(HCl) = c(H+).
That's it. There is no need to "interpret."
 
Students who become concerned with extreme pH's in water solution are more likely to miss the theory when they try to take a look at a pH for an extremely alkaline solution, excessive amount of hydroxide ions. pH relates to hydronium ion concentration related to dissociation of water. Borek or somebody can explain this better.
 
"Concentrated" hydrochloric acid that you buy is typically 37% HCl. That's about 10 M. So 4.41 M is certainly possible.
 
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mjc123 said:
"Concentrated" hydrochloric acid that you buy is typically 37% HCl. That's about 10 M. So 4.41 M is certainly possible.

Although its pH is not just minus log of concentration, as things get complicated because of the high ionic strength of the solution.

(@mjc123 I know you know, I just wanted it clearly stated in the thread).
 
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