Determining pH when given volume and concentration of a solution?

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Discussion Overview

The discussion revolves around determining the pH of a Tris solution given its volume and concentration, specifically in the context of a homework problem. Participants are exploring the implications of adding NaOH to the solution and the appropriate equations to use for calculating pH.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether the Henderson-Hasselbalch equation is appropriate for calculating pH in this scenario, given the volume and concentration of the solution.
  • Another participant seeks clarification on what is meant by "Tris solution (in acid form)" and whether it refers to a specific type of Tris buffer.
  • Several participants express confusion about the terminology used, particularly regarding the different forms of Tris and what is meant by "acid form."
  • A participant provides a link to a Wikipedia page on Tris, suggesting it may contain helpful information.
  • Another participant explains that Tris can exist as Tris base and Tris hydrochloride, indicating that the latter may be the form referenced in the problem.

Areas of Agreement / Disagreement

Participants generally express uncertainty about the terminology and the appropriate method for calculating pH, indicating that multiple competing views remain regarding the interpretation of "Tris in acid form" and the use of the Henderson-Hasselbalch equation.

Contextual Notes

The discussion highlights a lack of clarity regarding the definitions and forms of Tris, as well as the assumptions underlying the use of the Henderson-Hasselbalch equation in this context.

Violagirl
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Homework Statement



I'm stuck on these two problems:

A) IF you make a 50 mL of a 0.1 M Tris solution (in acid form), what will be the pH?

B) If you add 2 mL of 1 M NaOH to the above solution, what will be the pH?

Homework Equations



pH = pka + log [A/HA] Hendersen-Hasselbalch

The Attempt at a Solution



I'm not sure if HH is the right equation to use or not for this one when given both volume and concentration or if you add the NaOH to it. Help is greatly appreciated.
 
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Violagirl said:

Homework Statement



I'm stuck on these two problems:

A) IF you make a 50 mL of a 0.1 M Tris solution (in acid form), what will be the pH?

B) If you add 2 mL of 1 M NaOH to the above solution, what will be the pH?

Homework Equations



pH = pka + log [A/HA] Hendersen-Hasselbalch

The Attempt at a Solution



I'm not sure if HH is the right equation to use or not for this one when given both volume and concentration or if you add the NaOH to it. Help is greatly appreciated.

It would help if you could define what "Tris solution (in acid form)" is.
 
I'm not sure, that is the exact way that the question was asked...Is it referring to a Tris buffer of a 100% solution?
 
I can only repeat after Pranav-Arora - what does it mean "Tris in acid form"? What other forms can Tris have?
 
This might help you...
160px-Tris.png

http://en.wikipedia.org/wiki/Tris
 
Last edited:
You can buy tris which they call tris base (HOCH2)3CNH2, and you can buy tris hydrochloride (crystalline) (HOCH2)3CNH3+Cl-, I think the latter is what they must mean.
 

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