Buffer Solutions: How to Create and Maintain Optimal pH Levels?

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Discussion Overview

The discussion revolves around the creation and maintenance of buffer solutions, specifically focusing on the reactions involving weak acids and bases, their salts, and the resulting equilibrium states. Participants explore the conditions necessary for a solution to function as a buffer, including the presence of conjugate acid-base pairs.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant states that buffer solutions require a weak acid or base and its salt, questioning the absence of these components in their options.
  • Another participant outlines the products of three different reactions involving strong and weak acids and bases, suggesting that reaction 3 likely creates a buffer solution due to the ability to accept or donate protons.
  • A participant argues that for a buffer to exist, comparable amounts of conjugate acid and base are necessary.
  • One participant revises their stance on reaction 2, proposing that it can form a buffer solution due to the presence of HNO2 and NO2- in significant concentrations.
  • Participants inquire about the concentrations of the components present in the reactions, indicating a focus on quantitative aspects of buffer solutions.

Areas of Agreement / Disagreement

There is no consensus on the conditions required for a buffer solution, as participants express differing views on the necessity of conjugate acid-base pairs and the specific reactions discussed. Multiple competing perspectives remain unresolved.

Contextual Notes

Participants have not fully clarified the assumptions regarding the concentrations and specific conditions under which the reactions occur, leaving some aspects of the discussion open to interpretation.

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Homework Statement


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Homework Equations

The Attempt at a Solution


From what I know, to make buffer solutions you need a weak acid or base and it's salt. Non of the options has this. What am I missing?

Cheers!
 
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What is left after the reaction?
 
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For reaction 1, the products are: Cl-, NH4+, NH3, H+ (as HCl is strong acid while ammonia is weak base)
For reaction 2, the products are: Na+, H2O, NO2- (NaOH is strong while nitrous acid is weak. No HNO2 because the H+ will react to form water so equilibrium will shift to the right in equilibrium HNO2 → H+ + NO2-)
For reaction 3, the products are: NH3, NH4+, HNO2, NO2- (both are weak)

Reaction 3 is probably creates a buffer solution as they can accept or donate protons and the equilibrium will shift.
If acid was added to reaction 2, the NO2- will turn to nitrous acid but if base was added, nothing will happen, so not a buffer solution.
If acid was added to reaction 1, the equilibrium NH3 + H+ ↔ NH4+ will shift to the right and if base was added, the equilibrium will shift to the left so it is a buffer solution.

Answer is D.

Are my explanations correct?

Cheers!
 
Nope, you need a comparable amounts of conjugate acid and base for the buffer to exist.
 
I see, I change my mind on reaction 2. There will be around 0.5 M of HNO2 and NO2- so it will be a buffer solution. So then the answer is E?

Cheers!
 
What is present after the reaction in the 3rd mixture?
 
NH3, NH4+, HNO2, NO2-
 
In what (approximate at least) concentrations?
 

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