Disable the effect of HCl on the PH of solution?

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Discussion Overview

The discussion revolves around the challenge of measuring the pH of an amino acid compound in an acidic HCl solution. Participants explore methods to isolate the pH behavior of the amino group from the influence of HCl, considering various experimental approaches and theoretical concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the friend could study the amino compound separately to understand its pH behavior in water, potentially through titration.
  • Another participant emphasizes that performing a titration would help determine the pKa of the amino-containing compound, which could predict its behavior in various aqueous solutions.
  • A different viewpoint states that the concept of pH may not apply directly to the compound, proposing that pKa or pKb should be the focus instead.
  • The original poster expresses concern about neutralizing HCl with NaOH due to potential inaccuracies and seeks alternative methods to shield the HCl's effect on pH measurements.

Areas of Agreement / Disagreement

Participants generally agree on the importance of understanding the pKa or pKb of the amino acid, but there is no consensus on the best method to isolate the pH measurement from the HCl influence. Multiple competing views on experimental approaches remain.

Contextual Notes

The discussion does not resolve the limitations of measuring pH in the presence of strong acids or the assumptions regarding the behavior of the amino acid in different solvents.

Silex7
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Hi,
well my friend is in the final year graduation and he is working on a project a part of it is trying to detect the pH of a certain compound exist in acidic HCl solution, this compund don't remember its name for recent but it has the amino 'NH2" group this compund is in solution of HCL and he wants to detect the pH of the compound containing the amino group ONLY , but the problem is that HCl would alter the pH calculation raising it..so how can he detect a ph of the amino gp located in hcl solution without the conflicting of HCl in his calculations for the amino? he was thinking about neutralizing the HCl with NaOH so that effect of HCl is canceled but the problem is that this method sometimes is inaccurate and cause some errors..so is there any compound to be added so that it can let's say 'shield' the Hcl cancelling its effect on the ph?

thanks in advance
 
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Does your friend have a sample of the amino compound separate from the HCl ? He could study the compound separately first. He could measure pH of a few different concentrations of this compound. He could also perform a titration to obtain points for a titration curve. He would then know the pH behavior of this compound in water ( I assume water to be the exptected solvent).

By some chance, maybe another forum member could suggest how some method in a solvent other than water might be used - but I not know, this is a stretch.
 
Performing a titration on the solution is the best way to go. From the titration curve, you will be able to figure out the pKa of the amine-containing compound, and that will allow you to predict the behavior of the compound in any aqueous solution. Any introductory chemistry textbook should have information about how you would go about calculating the pKa of a compound from a titration curve.
 
No such thing as pH of the compound, what your friend is looking for is most likely pKa or pKb (these are ways of describing acid/base dissociation constants). Follow Ygg advice.
 

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