are acids or bases positively charged?

[myry]

I'm getting conflicting answers from different sources.

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[ltrain]

I'm getting conflicting answers from different sources.

If it is a strong acid or base, it will ionize in solution. Strong acids ionize into H+ ions and their counterparts and strong bases will ionize into OH- ions and their counterparts. That help?

 

[chanjurban]

It depends.

If it is positively charged, it is most likely an acid, especially if it has H in the formula. However, charge is not the deciding factor. An acid is something that has the ability to donoate protons (H+) or to accept electrons.

A base is something that has the ability to accept protons or to donate electrons.

Examples of acids: H3O+, HCl, BF3, H2SO4, H3PO4, H2PO4-.

Examples of bases: NH3, PO4-3, OH-, H2PO4-

Anjani

 

[Buckeye(OH)]

I'm getting conflicting answers from different sources.

What the person said above me is correct. It depends on the strength of the acid. HCl will dissociate into H+ and Cl- while something weak won't dissociate or will do so minimally.

 

[myry]

What about in terms of amino acids though? Which form (acidic or basic) is positively charged and which is negatively charged?

 

[flash]

this is hilarious...

see above, but my guess is that you should assume that acidic species is negatively charged after donating a proton b/c it lost a H+.

On amino acid q, depends on pH of environment. Amino end will take a proton, while carboxy end will donate. So, H3N+ and COO- at generally neutral pH.

Dude, this has got to be in your text.

 

[Buckeye(OH)]

What about in terms of amino acids though? Which form (acidic or basic) is positively charged and which is negatively charged?

Depends on the isoelectric point and where you are on the pH scale.

 

[Buckeye(OH)]

Depends on the isoelectric point and where you are on the pH scale.

Perhaps I should elaborate.

If I remember correctly, if you are below the isoelectric point, you will have a positive zwitterion. If @ the IP, you will be neutral and if above the IP, you will be negative.


Someone double-check, I'm rusty.

 

[iamgoaloriented]

I'm getting conflicting answers from different sources.

Acids lose protons or accept electrons, so if something is positively charged its more likely to be an acid.

Bases accept protons or donate electrons, so if something is negatively charged it is more likely to be a base.

There are factors to consider other than charge in determining if something can act as an acid or base, but for the purposes of your question I hope that helps.

A species can be neutral and act as an acid or a base though (e.g. NH3 base, AlCl3 acid, water can act as either).

 

[myry]

so according to Buckeye, if you are below the isoelectric point, you are at a lower pH and therefore the cationic form is acidic. Above the isoelectric point the anionic form is predominant, making the anionic form basic. Is this right?

 

[Siggy]

this is hilarious...

see above, but my guess is that you should assume that acidic species is negatively charged after donating a proton b/c it lost a H+.

On amino acid q, depends on pH of environment. Amino end will take a proton, while carboxy end will donate. So, H3N+ and COO- at generally neutral pH.

Dude, this has got to be in your text.

Yes, but after it donates the proton, then the species ceases to act as an acid and begins to act as its conjugate base. Strong acid=weak conjugate base. Weak acid=strong conjugate base.

Thus, HCl is an acid, but after it reacts the Cl- is actually a weak base.

 

[iamgoaloriented]

Perhaps I should elaborate.

If I remember correctly, if you are below the isoelectric point, you will have a positive zwitterion. If @ the IP, you will be neutral and if above the IP, you will be negative.


Someone double-check, I'm rusty.

All amino acids can act as either an acid or a base because they have a carboxyl group than can lose protons and an amino group than can gain protons/donate electons.

Amino acids that are said to be basic have an extra amino group. They will have isoelectic points at a pH higher than physoilogical pH and be positively charged at physilogical pH (you need a more alkaline environment to obtain an overall neutral charge because the amino group can hold onto another proton).

Amino acids that are said to be acidic have an extra carboxyl group. They will have isoelectic points at a pH lower than physoilogical pH and be negatively charged at physilogical pH (you need a more acidic environment to obtain an overall neutral charge because the carboxyl groups can more easily lose a proton).

 

[Medikit]

You are getting different answers because you are looking at the question all wrong. It's not about charge it's about the ability to donate or receive electrons. For the hell of it: Sulfurous acid is negatively charged and can behave like an acid depending on the pH. Hydroxide is negatively charged and is a base. N-Isopropylethylenediamine can be positively charged and behave like a base at certain pH's. Hydronium is positively charged and an acid.

 

[Siggy]

Technically speaking, it all depends on the pH level. If you get the pH level low enough, then even some strong acids would act as basses. Generally, though, if it is positive it is an acid because it will want to lose the proton (acids are proton donors) to become a neutral charge. The oppsite occurs with negative molecules. They want to accept the proton because it will make them neutral.

But, as was said earlier, the weak acids and weak bases are kinda of tricky because anything around a pH of 7 tends to be willing to go either way (example: H2O can be OH- or H3O+ depending on the pH level of the solution).

 

[patzan]

you are all arguing over different definitions. Lewis acids are electron acceptors. There are also Bronsted-Lowry and Arrhenius definitions (proton donors, etc.)

 

[Medikit]

you are all arguing over different definitions. Lewis acids are electron acceptors. There are also Bronsted-Lowry and Arrhenius definitions (proton donors, etc.)

Bronsted-Lowry is contained within the lewis acid description.