Equilibrium and Highest Concentration of Carbonic Acid

  • Thread starter Thread starter Hevonen
  • Start date Start date
  • Tags Tags
    Equilibrium
Click For Summary

Discussion Overview

The discussion revolves around the equilibrium concentrations of species in a solution of carbonic acid, specifically focusing on which species is present in the highest concentration. Participants explore the behavior of weak acids, their dissociation, and the implications for concentration ratios.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant asserts that H2CO3 is the species present in the highest concentration, while another believes that H+ should be considered due to its relation to the dissociation of carbonic acid.
  • Several participants reference the dissociation constant (Ka) of carbonic acid, noting that it is a weak acid with a Ka of about 1.8*10^(-5), which influences the extent of dissociation.
  • There is a discussion about the percentage of carbonic acid that will dissociate and its implications for the concentrations of H+ and H2CO3.
  • One participant questions whether it is always the case that the initial concentration of a weak acid remains the highest, suggesting that it may depend on the strength and concentration of the acid.
  • Another participant notes that weak acids tend to remain largely undissociated in solution, indicating that they ionize to a small extent.
  • There is a suggestion that once the concentration of the undissociated form falls below that of the dissociated form, H+ will dominate the solution.

Areas of Agreement / Disagreement

Participants express differing views on whether H2CO3 or H+ is present in the highest concentration, indicating a lack of consensus on this point. The discussion includes multiple competing perspectives on the behavior of weak acids and their dissociation.

Contextual Notes

Participants reference the dissociation constant and the concentration of carbonic acid, but there are unresolved assumptions regarding the specific conditions of the solution and the extent of dissociation.

Who May Find This Useful

This discussion may be of interest to students and professionals in chemistry, particularly those studying acid-base equilibria and the behavior of weak acids in solution.

Hevonen
Messages
54
Reaction score
0
[SOLVED] Equilibrium and Highest [A]

Relevant equation
Consider the following equilibria in 0.10 moldm−3 carbonic acid.
(In attachment)
Which species is present in the highest concentration?
A. H2CO3 (aq)
B. H+(aq)
C. H(CO3)− (aq)
D. (CO3)2− (aq)
The attempt at a solution
The right answer is A but I would think that B would be the right answer because as carbonic acid includes 2 H+ cations so doubling their concentration. Please, say your comment on this problem, why only A is right.

Thank you in advance!
 

Attachments

Physics news on Phys.org
Understand that carbonic acid is a weak acid, Ka = about 1.8*10^(-5). Based on this, what percent of the carbonic acid will disassociate?
 
symbolipoint said:
Understand that carbonic acid is a weak acid, Ka = about 1.8*10^(-5). Based on this, what percent of the carbonic acid will disassociate?
Good point. I got for [H+]= 10^-3, as this is much smaller than 0.1 so H2CO3 is in greatest concentration.

Is it always with weak acids that the concentration of initial acid is highest?
 
weak acids tend to remain as molecules in solutions, they ionise to a small extent.
 
Hevonen said:
Is it always with weak acids that the concentration of initial acid is highest?

Depends on their strength and concentration, there is no one, general rule. However, for obvious reasons (stoichiometry) once undissociated form fails below concentration of dissociated form, it is H+ that starts to dominate the solution :)



 

Similar threads

Chemistry How to calculate pH at equivalence point using this alternative?
  • · Replies 7 ·
Replies
7
Views
2K
Chemistry How to take into account autoprotolysis in weak base solution?
  • · Replies 8 ·
Replies
8
Views
3K
Chemistry How do we interpret the steps in the algorithm to balance a redox equation?
  • · Replies 7 ·
Replies
7
Views
3K
Calculate Equilibrium Constant for Polyprotic Acid Reaction
  • · Replies 2 ·
Replies
2
Views
2K
What happens if an acid is added to this buffer?
  • · Replies 2 ·
Replies
2
Views
5K
How Does Le Chatelier's Principle Affect Reactions in Chlorine Water Systems?
  • · Replies 1 ·
Replies
1
Views
2K
What is the Hydroxide Ion Concentration in an Ionic Equilibrium Problem?
  • · Replies 7 ·
Replies
7
Views
3K
How Do You Calculate NaCH3COO Concentration and Predict pH at Equivalence Point?
  • · Replies 4 ·
Replies
4
Views
4K
Factors Affecting Equilibrium Questions.
  • · Replies 12 ·
Replies
12
Views
4K
Lowest concentration of ethanoate ions
  • · Replies 2 ·
Replies
2
Views
2K