Aqueous solutions and whether they are acidic/basic/neutral

In summary, the conversation discusses the concept of acid and base in different contexts. It defines basic/acidic compounds and explains their behavior in aqueous solutions. It also addresses the relative strength of basicity/acidity and the importance of defining these terms with respect to a specific substance or solution. The conversation highlights the complexity of acid-base chemistry and the need for clear definitions in understanding these concepts.
  • #1
~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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  • #2
Define basic/acidic compound.
 
  • #3
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
 
  • #4
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.
 
  • #5
~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 ( [tex]CH_3COOH[/tex] ) for example is a base with respect to [tex]H_2SO_4[/tex] . If you mix them, you will find [tex]HSO_4^-[/tex] and [tex]CH_3COOH_2^+[/tex].
 
  • #6
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 ( [tex]CH_3COOH[/tex] ) for example is a base with respect to [tex]H_2SO_4[/tex] . If you mix them, you will find [tex]HSO_4^-[/tex] and [tex]CH_3COOH_2^+[/tex].

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)
 
  • #7
~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.
 
  • #8
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?
 
  • #9
~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...
 
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  • #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
 

1. What is an aqueous solution?

An aqueous solution is a solution where the solvent is water. In other words, it is a mixture of a substance (called the solute) and water (called the solvent). Aqueous solutions are very common in nature and are used in many scientific experiments and industrial processes.

2. What does it mean for an aqueous solution to be acidic?

An aqueous solution is considered acidic if it has a high concentration of hydrogen ions (H+) compared to hydroxide ions (OH-). This results in a low pH value (less than 7). Acids are often sour-tasting and can react with metals to produce hydrogen gas.

3. How can you determine if an aqueous solution is basic?

An aqueous solution is considered basic if it has a high concentration of hydroxide ions (OH-) compared to hydrogen ions (H+). This results in a high pH value (greater than 7). Bases are often bitter-tasting and can feel slippery to the touch.

4. What is a neutral aqueous solution?

A neutral aqueous solution has an equal concentration of hydrogen ions (H+) and hydroxide ions (OH-), resulting in a pH of 7. This means that the solution is neither acidic nor basic. Pure water is an example of a neutral aqueous solution.

5. How can you change the pH of an aqueous solution?

The pH of an aqueous solution can be changed by adding substances that either donate or accept hydrogen ions. Acids can lower the pH, while bases can raise the pH. Additionally, diluting the solution or adding a buffer can also affect the pH of an aqueous solution.

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