Buffer solutions acid or base

In summary, the conversation discusses the formation of buffer solutions and the products of three reactions. It is determined that reaction 3 creates a buffer solution due to the presence of both a weak acid and its conjugate base. However, for reaction 2, the presence of a strong base and weak acid may lead to the formation of a buffer solution depending on the concentrations. Ultimately, the correct answer is determined to be D, with the approximate concentrations of NH3 being 0.5 M and HNO2 and NO2- being equal.
  • #1

TT0

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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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  • #2
What is left after the reaction?
 
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  • #3
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!
 
  • #4
Nope, you need a comparable amounts of conjugate acid and base for the buffer to exist.
 
  • #5
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!
 
  • #6
What is present after the reaction in the 3rd mixture?
 
  • #7
NH3, NH4+, HNO2, NO2-
 
  • #8
In what (approximate at least) concentrations?
 

What is a buffer solution?

A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added. It consists of a weak acid and its conjugate base (or a weak base and its conjugate acid) in roughly equal amounts.

How do buffer solutions work?

Buffer solutions work by utilizing the principle of Le Chatelier's principle. When a small amount of acid or base is added to a buffer solution, the equilibrium between the weak acid and its conjugate base is shifted, causing a minimal change in pH.

What is the purpose of a buffer solution?

The purpose of a buffer solution is to maintain a constant pH level in a solution. This is important in many biological and chemical processes as even small changes in pH can have a significant impact on the outcome of a reaction.

How do you prepare a buffer solution?

A buffer solution can be prepared by mixing a weak acid (or base) with its conjugate base (or acid) in a 1:1 ratio. The concentration of the components depends on the desired pH level of the buffer solution.

What is the pH range of a buffer solution?

The pH range of a buffer solution is typically within one pH unit of the pKa of the weak acid or base used. This ensures that the buffer solution is most effective in resisting changes in pH.

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