Test tube containing small portion of aspirin

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Discussion Overview

The discussion revolves around an experiment involving aspirin, its chemical behavior in different pH environments, and its activity in the stomach versus the intestines. Participants explore the implications of pH on the solubility and absorption of aspirin and its conversion to salicylic acid.

Discussion Character

  • Experimental/applied, Conceptual clarification, Technical explanation

Main Points Raised

  • One participant describes an experiment where aspirin was tested with NaOH and HCl, resulting in a positive phenol test with FeCl3, suggesting the presence of phenolic compounds.
  • Another participant questions the pH levels of the stomach and intestines, seeking clarification on their differences.
  • It is noted that the stomach has a lower pH (acidic) compared to the intestines, which are more basic.
  • Participants discuss how the acidic environment of the stomach affects the ionization of aspirin, with implications for its solubility and absorption in the intestines.
  • One participant proposes that if aspirin is ionized in the intestines, it may be more soluble and thus more readily absorbed, leading to its activity in that environment.
  • Another participant suggests that the NaOH treatment mimics intestinal conditions, allowing for the conversion of aspirin to salicylic acid, which is confirmed by the positive phenol test.

Areas of Agreement / Disagreement

Participants generally agree on the differences in pH between the stomach and intestines and their implications for aspirin's behavior, but there is no consensus on the specific mechanisms or the extent of aspirin's activity in the intestines versus the stomach.

Contextual Notes

There are unresolved questions regarding the exact effects of pH on the ionization and absorption of aspirin, as well as the implications of the experimental results for understanding aspirin's activity in the body.

stanton
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I had an experiment. A test tube containing small portion of aspirin was prepared. NaOH was added to the solution, and then HCl was added. when I mixed FeCl3 with the solution, the solution turned intense purple.
This result is the positive test for phenols.

And why does this result proves that the aspirin is active in intestine? I cannot understand. I thought the aspirin is most active in stomach, because I though the acid converts aspirin to salicylic acid?
 
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What is the pH of the stomach? How about lower down in the intestines?
 


stomach has lower ph than the intestine(acidic). intestine is basic, right?
 


Yes. The stomach is acidic and the intestines are somewhat basic. This means that aspirin is not ionized in the stomach and is ionized further down the intestines. How might this affect solubility? Absorption?
 


If the ASA is ionized in intestine, it might mean the ASA is dissolved. So intestine can absorb this ASA. Then the ASA is very active in intestine. And NaOH in my experiment converted the ASA to sali acid(Test tube with NaOH is similar to the environment of intestine). And although the HCl was added lastly, the ASA is not very affected, so it showed phenol test to be positive. (salicylic acid is a substituted phenol) I think I am getting it. :) Thank you!
 

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