Reacting OH- with CO2 in a Buffer Solution: Which Molecule Takes Priority?

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Discussion Overview

The discussion revolves around the behavior of hydroxide ions (OH-) when added to a buffer solution containing carbon dioxide (CO2) and bicarbonate (HCO3-). Participants explore the reactions that occur and the priority of interactions between OH-, CO2, and H+. The scope includes conceptual understanding of acid-base reactions and equilibrium principles.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes the buffer equilibrium involving CO2, HCO3-, and H+, questioning why OH- reacts with CO2 instead of H+.
  • Another participant challenges the proposed reaction between CO2 and OH-, suggesting it cannot be balanced, which raises doubts about its occurrence.
  • A participant asks what specifically happens when OH- is added to the buffer solution.
  • It is suggested that OH- should react with the predominant acid in the solution, though the identity of the acid is questioned.
  • Concerns are raised about determining the acid in cases where it is not obvious, indicating a need for clarity in such scenarios.
  • One participant asserts that OH- generally reacts with H+, which may influence the equilibrium of other acid/base reactions according to LeChatelier's principle.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the specific reactions that occur when OH- is added to the buffer solution. There is no consensus on which species OH- reacts with first, and multiple competing views remain on the nature of the acid in the solution.

Contextual Notes

Limitations include the ambiguity in identifying the predominant acid and the unresolved nature of the proposed reactions involving CO2 and OH-. The discussion reflects varying assumptions about acid-base interactions in buffer solutions.

semc
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Here's the buffer solution H2O + CO2 <=> HCO3- + H+ so the question is why when OH- is added to the solution it reacts with CO2 to get HCO3- and H+ :confused: how do you know which one will OH- react with?Why doesn't the OH- react with the H+ :confused:
 
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Are you telling that reaction that takes place is

CO2 + OH- <-> HCO3- + H+

It can't be balanced (which usually means that such reaction doesn't take place).
 
So what happen when OH- is added to the buffer?
 
It should react with the predominant acid in the solution.
 
ermz...so how do you know which one is the acid?I mean in cases where the acid and base is not so obvious?
 
In general you may safely assume that OH- always reacts with H+. That in turn may move equilibrium of other reactions (acid/base dissociations) according to the LeChatelier's principle.
 

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