Dissociation degree of polyprotic acids

In summary, the formula derived from the Henderson-Hasselbach equation can be used to calculate the dissociation degree of both monoprotic and polyprotic acids. This formula is a rearranged form of the dissociation constant definition and is useful for analyzing endpoint detection accuracy in acid/base titrations.
  • #1
ComptonFett
8
0
I can quickly calculate the dissociation degree of a monoprotic acid with the formula below (derived from the Hendersson-Hasselbach equation). I don't see any reason why this would not work also for polyprotic acids but I would like to confirm that it does. I would appreciate it if someone could confirm/disconfirm this. Thanks.

\begin{align}
& pH=pKa+\log \frac{A^{-}}{HA} \\
& \log \frac{A^{-}}{HA}=pH-pKa \\
& \frac{A^{-}}{HA}=10^{pH-pKa} \\
\end{align}
 
Chemistry news on Phys.org
  • #2
Yes it will work - pH and pKa are enough to calculate ratio of acid and conjugate base concentrations.

As Henderson-Hasselbalch equation is just a rearranged form of the dissociation constant definition, formula you derived is also just a rearranged form of the dissociation constant definition. It is quite useful in the analysis of the endpoint detection accuracy (see discussion of acid/base titration indicators where the same formula is used).
 
  • #3
Cheers!
 

FAQ: Dissociation degree of polyprotic acids

1. What is the dissociation degree of a polyprotic acid?

The dissociation degree of a polyprotic acid is the measure of the extent to which the acid dissociates in a solution. It is expressed as a percentage, with 100% representing complete dissociation and 0% representing no dissociation.

2. What factors affect the dissociation degree of polyprotic acids?

The dissociation degree of polyprotic acids can be affected by factors such as the strength of the acid, the concentration of the acid, the presence of other ions in the solution, and temperature.

3. How is the dissociation degree of polyprotic acids calculated?

The dissociation degree of polyprotic acids can be calculated using the Henderson-Hasselbalch equation, which takes into account the acid dissociation constant (Ka) and the concentrations of the acid and its conjugate base in the solution.

4. What is the significance of the dissociation degree of polyprotic acids?

The dissociation degree of polyprotic acids is important in determining the strength of the acid and its ability to donate protons in a solution. It also affects the pH of the solution and can impact the reactivity of the acid in certain chemical reactions.

5. Can the dissociation degree of polyprotic acids change?

Yes, the dissociation degree of polyprotic acids can change depending on the conditions of the solution. For example, increasing the concentration of the acid or decreasing the pH can lead to a higher dissociation degree, while the presence of other ions can decrease the dissociation degree.

Similar threads

Henderson Hasselbalch Equation - Request for Clarification
Replies
8
Views
1K
Deriving the Henderson-Hasselbalch equation
Replies
6
Views
1K
Citric Acid pKa: Calculate pH of Molar Concentration
Replies
7
Views
9K
Can I combine an Acid dissociation with autoionization of H2O?
Replies
6
Views
2K
The weak acid conjugate base - something i can't understand.
Replies
4
Views
3K
Isoelectric Point: Definition & Calculation
Replies
5
Views
2K
Calculating pKa when pH is known
Replies
2
Views
8K
Acid Base Confusion: Solutions to Common Questions
Replies
2
Views
1K
Understanding pKa of Fatty Acids
Replies
2
Views
15K
Chemistry Moles of NaOH to Create Buffer Solution pH=6 in 0.42M Ethanoic Acid
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top