Aqueous solutions and whether they are acidic/basic/neutral

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Discussion Overview

The discussion revolves around the characterization of aqueous solutions formed by adding acidic or basic compounds to water. Participants explore definitions of acidity and basicity, the context of these definitions, and the implications for the resulting solution's pH. The conversation touches on theoretical aspects and the nuances of chemical behavior in aqueous environments.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question whether adding an acidic or basic compound to water will definitively result in an acidic or basic solution, suggesting that context matters.
  • Definitions of acidic and basic compounds are discussed, including Lewis and Bronsted-Lowry theories, indicating that the classification may depend on the specific context or reference point.
  • Acetic acid is used as an example to illustrate that it can be considered a base in relation to stronger acids like sulfuric acid, raising questions about the relative strength of acids and bases.
  • Participants note that the behavior of compounds in solution can vary, with buffer solutions potentially leading to neutral, acidic, or basic outcomes depending on their composition and interactions.
  • There is an acknowledgment that the professor's definition of acidic/basic compounds could influence the interpretation of the question posed.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the definitions and implications of acidity and basicity in aqueous solutions. There is no consensus on a definitive answer to the original question, as it remains contingent on the definitions applied and the context of the discussion.

Contextual Notes

The discussion highlights the importance of definitions and context when classifying compounds as acidic or basic, with implications for the resulting solution's properties. The conversation reflects varying interpretations of chemical behavior in aqueous solutions.

~christina~
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This isn't a homework question but a general question which I should know the answer to but am not sure.

If you have a basic/acidic compound and add it to water to form an aqueous solution, the water should turn basic/acidic respectively, right? no exception?

Thank you
 
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Define basic/acidic compound.
 
Borek said:
Define basic/acidic compound.

Lewis Base/Acid
Acid- accepts e- pair
Base- donates e- pair

Bronsted-Lowry Acid/Base
Acid -donates H+ ion
Base- accepts H+ ion
 
I think Borek was thinking in the context of an aqueous solution.

How would one characterize HBr or H2SO4, NaAc (Ac = acetate), or BF3, anhydrous, i.e. pure and out of water?

BF3 is interesting because it is used in gaseous neutron detectors, particularly with B enriched in B-10.
 
~christina~ said:
This isn't a homework question but a general question which I should know the answer to but am not sure.

If you have a basic/acidic compound and add it to water to form an aqueous solution, the water should turn basic/acidic respectively, right? no exception?

Thank you
Borek is right.
Let's make another example: acetic acid. Is it a base or an acid? Would you say acid? With respect to what? If your answer is "with respect to water" then your question is meaningless...
In general, every substance can be acid or base. Acetic acid ( CH_3COOH ) for example is a base with respect to H_2SO_4 . If you mix them, you will find HSO_4^- and CH_3COOH_2^+.
 
lightarrow said:
Borek is right.
Let's make another example: acetic acid. Is it a base or an acid? Would you say acid? With respect to what? If your answer is "with respect to water" then your question is meaningless...
In general, every substance can be acid or base. Acetic acid ( CH_3COOH ) for example is a base with respect to H_2SO_4 . If you mix them, you will find HSO_4^- and CH_3COOH_2^+.

Well, this would be comparing the relative strength of basicity/acidity of one compound to another...or the relative willingness of one compound to accept vs give away a H+ ion. (ex. H20 can gain a H+ to become H30+ or it can loose a H+ to have OH- ion)
 
~christina~ said:
Well, this would be comparing the relative strength of basicity/acidity of one compound to another...or the relative willingness of one compound to accept vs give away a H+ ion. (ex. H20 can gain a H+ to become H30+ or it can loose a H+ to have OH- ion)
Yes, so, acetic acid, for example, can be considered a base. If you put it on water how will the solution become, acidic or basic? You see that your question doesn't have a definite solution until you give a definition of acid or base, that is, acid or base with respect to something.
 
lightarrow said:
Yes, so, acetic acid, for example, can be considered a base. If you put it on water how will the solution become, acidic or basic? You see that your question doesn't have a definite solution until you give a definition of acid or base, that is, acid or base with respect to something.

I understand. It's just that a professor asked me this question and did not ask me this with respect to anything. I do suspect that it would be respect to water, if you're placing it in water?
 
~christina~ said:
I understand. It's just that a professor asked me this question and did not ask me this with respect to anything. I do suspect that it would be respect to water, if you're placing it in water?
Usually it's so. Then your question has an obvious answer.
As you see, it really depends on how your professor define a "basic/acidic" compound. It could even define as "acidic" a compound which, in water solution, reacts (almost) quantitatively with a strong base, but a buffer compound can do it as well, and if you dissolve a buffer compound in water the solution can become acidic, basic, neutral...
 
Last edited:
  • #10
lightarrow said:
Usually it's so. Then your question has an obvious answer.
As you see, it really depends on how your professor define a "basic/acidic" compound. It could even define as "acidic" a compound which, in water solution, reacts (almost) quantitatively with a strong base, but a buffer compound can do it as well, and if you dissolve a buffer compound in water the solution can become acidic, basic, neutral...

Yes. I understand what you're saying. It was just that I was probably thinking about it a little too simply.

Thanks lightarrow
 

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