Calculate pH of 4.41 M HCl Water Solution

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Discussion Overview

The discussion centers on calculating the pH of a 4.41 M HCl water solution and whether such a high molarity solution is feasible. Participants explore the implications of strong acid behavior and the definition of pH in this context.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how to calculate the pH of a 4.41 M HCl solution and whether such a solution can exist.
  • Another participant notes that calculating pH using -log(4.41) yields a negative value, expressing uncertainty about its interpretation.
  • Some participants affirm that negative pH values are possible, particularly in the context of strong acids with concentrations greater than 1 M.
  • There is a discussion about the definition of pH, with one participant stating that for strong acids like HCl, the concentration of HCl can be equated to the concentration of H+ ions.
  • One participant mentions that concentrated hydrochloric acid is typically around 10 M, suggesting that 4.41 M is indeed possible.
  • Another participant adds that the pH calculation is more complex due to the high ionic strength of such solutions, indicating that the relationship is not straightforward.

Areas of Agreement / Disagreement

Participants generally agree that a 4.41 M HCl solution can exist, but there is no consensus on the implications of its pH calculation, particularly regarding the effects of ionic strength and the interpretation of negative pH values.

Contextual Notes

Participants note that the behavior of pH in highly concentrated solutions may not follow simple calculations due to factors like ionic strength, which are not fully resolved in the discussion.

CroSinus
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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

Homework Equations

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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