How to Prepare a Buffer Solution with a pH of 12.50 Using Given Reagents?

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Discussion Overview

The discussion revolves around the preparation of a buffer solution with a target pH of 12.50 using specific reagents. Participants explore the feasibility of creating such a buffer, the appropriate equations to use, and the role of the available chemicals in achieving the desired pH.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about how to prepare the buffer solution with the given reagents.
  • Another suggests using the Henderson-Hasselbalch equation to determine the pH of the buffer solution.
  • A different participant argues that the Henderson-Hasselbalch equation is not applicable due to the lack of equilibrium constants (Ka and Kb) and states that strong acids and bases do not create buffer solutions.
  • Another participant counters that equilibrium constants can be found in chemistry literature and that NaH2PO4 can serve as the buffering agent, with strong acids and bases used to adjust the pH.
  • A later reply acknowledges the potential use of the Henderson-Hasselbalch equation but expresses confusion about the nature of the buffer, suggesting that NaH2PO4 would lead to an acidic buffer solution and raises questions about the classification of acids based on their molecular structure.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the applicability of the Henderson-Hasselbalch equation or the nature of the buffer solution. Multiple competing views regarding the preparation and classification of the buffer remain unresolved.

Contextual Notes

There are limitations regarding the availability of equilibrium constants and the definitions of strong acids and bases as they relate to buffer solutions. The discussion also reflects uncertainty about the classification of NaH2PO4 in this context.

Erinyes83
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Got a tough problem I have no clue how to do.

I have to prepare 500mL of a buffer solution with a pH of 12.50 and must be at least .10 M.

The only reagents I have are:
solid sodium dihydrogen phosphate dihydrate NaH2PO4 x (H2O)2
Distilled water
1.00 M NaOH(aq)
1.00 M HCL(aq)

Not all reagents need to be used. If I could get some help on how to do this problem, anything would be aprreciated.
 
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did you try the henderson-hasselbach equation?
 
Hederson-Hasselbach wouldn't work because you don't have any of the equillibrium constants such as Ka and Kb
I think its impossible because strong acids and strong bases don't create buffer solutions
 
Equilibrium constants can be looked up in chemistry books, and the NaH2PO4 is the buffering agent. The strong acid and strong base are for equilibrating it to the right buffering pH.
 
I see it now, my apologies, Henderson-Hasselbach would be in order. I believe the NaH2PO4 would ionize in water to form Phosphoric Acid and Sodium Phosphate. Then of course using the equation aformentioned to determine the pH. Then I'm afraid that i am baffled, because that would be an acidic buffer solution, and following a rule that was taught to me, an acid with 2 more oxygens then hydrogens is a strong acid, but there are exceptions and this may be one of them.
 

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