Finding the pH of a buffered System

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In summary, a buffer system using TRIS and TRISH+ is prepared with concentrations of 0.60M and 0.30M respectively. The pH of this system can be calculated using the Henderson-Hasselbalch equation, which is a rearranged version of the dissociation constant equation. The Ka for TRISH+ is 1.20 x 10^-6. By plugging in the values into the Henderson-Hasselbalch equation, the pH of the buffered system can be determined.
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Glitche
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1. A buffer system commonly used in the biochemistry lab uses a substance abbreviated TRIS, and it's conjugate acid TRISH+. A Buffer is prepared with [TRIS] = 0.60M and
[TRISH+]= 0.30M. What is the pH of this buffered System? The Ka for TRISH+ is 1.20 x 10^-6



[H+]=Ka [HA]/[A-] (Equation Attached)



3. I know the answer because I am studying off of a practice exam our professor gave to us, but I'd like to know how to solve it. The method I tried was [(1.20x10^-6)*(0.60/0.30)].

Thank you in advance!
 

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Equation you listed is just a rearranged version of the dissociation constant. It can be modified even further, yielding so called Henderson-Hasselbalch equation:

[tex]pH = pK_a + \log \frac {[A^-]}{[HA]}[/tex]

Once you have it it is just a plug and chug. You just have to understand what is the acid and what is the conjugate base in the case of TRIS.
 

FAQ: Finding the pH of a buffered System

1. What is a buffered system?

A buffered system is a solution that resists changes in pH when small amounts of acid or base are added. It contains a weak acid and its conjugate base, or a weak base and its conjugate acid.

2. How do you find the pH of a buffered system?

The pH of a buffered system can be found using the Henderson-Hasselbalch equation: pH = pKa + log ([base]/[acid]), where pKa is the dissociation constant of the weak acid, and [base] and [acid] are the concentrations of the base and acid in the solution, respectively.

3. What is the role of a buffer in a solution?

A buffer helps maintain the pH of a solution by neutralizing any added acid or base, preventing drastic changes in pH. It also helps keep biological systems, such as blood, within a narrow pH range for optimal function.

4. How does temperature affect the pH of a buffered system?

The pH of a buffered system is relatively unaffected by changes in temperature, as long as the temperature remains within a reasonable range. However, extreme temperatures can cause denaturation of the buffer components, leading to a change in pH.

5. Can a buffer maintain a constant pH in any situation?

No, a buffered system has a limited capacity to maintain a constant pH. If large amounts of acid or base are added, the buffer may become overwhelmed and unable to neutralize all of the added ions, resulting in a change in pH.

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