[BetaAmyloid]

Hi,

I had a couple questions about neutralization reactions:

(1) Do ALL or MOST neutralization reactions yield aqueous salts and water? (HA + BOH -> AB_(aq) +H₂O_(aq))

(2) If weak acids are strongs bases and strong bases are weak acids, why do chemists leave weak acids in undissociated forms within an equation while strong bases are dissociated within an equation?

(3) Does a weak base and weak acid react with one another normally? I know this should be a yes, but since weak acids/bases do not dissociate well, then I had doubts on if they react.

(4) Another random question about light spectroscopy:
Why are we able to use the spectra wavelengths of helium to predict those of hydrogen? Is this because both only have electrons that have grounds states at n=2? I am somewhat confused on this - I know shells (orbitals) begin at n=1 and I assume that n=2 (ground state) from some n=x (excited state) is visible light.

(5) Another random question about x-rays and other extremely high frequencies:
If x-rays and up have such high frequencies and emit such high temperatures at the point where the wavelength is at its peak directed on to the object at which it is being aimed, then why do we not feel heat or feel burned when having something such as an x-ray taken?


These aren't homework questions by the way, these are just questions I had myself.

Thanks.

[Schrödinger]

(1) All Bronsted-Lowry neutralization reactions (i.e., ones that involve a Bronsted-Lowry acid and a Bronsted-Lowry base) yield aqueous salts and water... The reason the salt is aqueous is the mere presence of water

(2)Weak acids are not strong bases and Strong bases are not weak acids. Misconception

(3)Yeah. They do react. Acetic acid and ammonium hydroxide would be an example. Reaction does occur, though. In such reactions, dissociation of water becomes a reaction worth consideration.. Please correct me if I am wrong


I'm really sorry I couldnt answer the other 2 questions now.. I'm in a hurry

[rabolisk]

(1) Do ALL or MOST neutralization reactions yield aqueous salts and water? (HA + BOH -> AB_(aq) +H₂O_(aq))

By aqueous salts, do you mean salts that are dissolved? If so, then the salt that is produced is not necessarily soluble in water, and you can get a precipitation. Sometimes, aqueous neutralization reactions don't appear to yield water (e.g. NH₃ + HCl   NH₄Cl), but remember that since the environment itself is aqueous, by definition, water is the solvent, and is thus, present.

(2) If weak acids are strongs bases and strong bases are weak acids, why do chemists leave weak acids in undissociated forms within an equation while strong bases are dissociated within an equation?

This is not true. Weak acids are not strong bases, and strong bases are not weak acids. Even a conjugate base of most weak acids is a weak acid. Only a conjugate base of an acid that is extremely weak (comparable to water) is a strong base.

(3) Does a weak base and weak acid react with one another normally? I know this should be a yes, but since weak acids/bases do not dissociate well, then I had doubts on if they react.

They do react, but it will be an equilibrium reaction which favors the side with the weaker acids.
HA + B   A^- + BH⁺.
Since a conjugate acid of a weak base is also an acid, BH⁺ is an acid. By the same reasoning A^- is also a base. So in both sides you have an acid and a base. The side that will be favored is the one which results in the weaker acid and the weaker base. Note that it is always the case (prove this to yourself!) that the side with the weaker acid is also the side with the weaker base.

(4) Another random question about light spectroscopy:
Why are we able to use the spectra wavelengths of helium to predict those of hydrogen? Is this because both only have electrons that have grounds states at n=2? I am somewhat confused on this - I know shells (orbitals) begin at n=1 and I assume that n=2 (ground state) from some n=x (excited state) is visible light.

I'm a little unclear on what you're asking. The ground state of electrons in both atoms is at n=1...

Let me think about (5) for a while.

[BetaAmyloid]

Thanks guys for the quick responses!

(1) Okay, so all Bronsted-Lowry neutralization reactions usually yield aqueous salts (ionized) and water; however, Lewis neutralization reactions can yield aqueous or solid salts combined with or without the presence of water. Is that right?

(2) Yeah, sorry guys. I was thinking about conjugate acids and bases. Confused myself!

(3) Okay, so take:

NH₄OH + CH₃CO₂H CH₃CO₂^- + NH₄⁺ + H₂O

Weak acid and weak base reactants yield weak acid and weak base products. I am assuming the right side yields the weaker acid and base since the acetate ion has one less hydrogen ion and ammonium ion has one less hydroxide ion plus the water meaning the right side is favored. Is that right? Also, is there a significant percentage higher of products being favored in this reaction than reactants?

(4) I understand that the ground state is n=1 in normal situations of each element. However, in this experiment, we are assuming that the electron is falling from n=x where x is any orbital higher than 2 and is falling back down to n=2 which will allow the light emitted to be in the range of visible light on the electromagnetic spectrum. We are using the spectra of helium to create a calibration curve of wavelength vs. scale reading and then finding a scale reading on the hydrogen spectra to find the unknown wavelength of it's spectra using the generated calibration curve. I guess I am asking: How is this possible if the two elements are not the same? Is it because each element has electrons only within the first shell in normal environment? If it were a larger element on the periodic table then electron shielding, effective nuclear charge, and all the other effects on electrons (I have forgotten most of them) will be different do to the multi-electron effect of the element's structure.

(5) Alright!

Thanks.

[rabolisk]

(1) Okay, so all Bronsted-Lowry neutralization reactions usually yield aqueous salts (ionized) and water; however, Lewis neutralization reactions can yield aqueous or solid salts combined with or without the presence of water. Is that right?

All Bronsted-Lowry neutralization reactions yield salt and water. The salt may or may not precipitate out.

I am assuming the right side yields the weaker acid and base since the acetate ion has one less hydrogen ion and ammonium ion has one less hydroxide ion plus the water meaning the right side is favored.

I don't see how you could assume that. It is true that for this reaction, the products will be favored heavily, but you could only know that by knowing pKa values.

[Borek]

All Bronsted-Lowry neutralization reactions yield salt and water.

Sometimes, aqueous neutralization reactions don't appear to yield water (e.g. NH₃ + HCl  NH₄Cl)

This is getting confusing 

I think we should start forcing The Cancer Curer to explain what he means by aqueous salts, I guess that's the source of the problem - everyone thinks about something different.

[Borek]

If x-rays and up have such high frequencies and emit such high temperatures at the point where the wavelength is at its peak directed on to the object at which it is being aimed

X-rays don't "emit high temperatures". Yes, single X-ray photon carries a lot of energy, but to heat up something you still need a lot of such photons. It is energy density that counts, not energy carrier (well, to some extent energy carrier is important - but that's another story).

Think about a difference between reading lamp in your bedroom and laser cutting metal sheets in the factory. They both use visible light.

[BetaAmyloid]

Thanks again guys.

What I think when I think of an aqueous salt: Dissociable/Ionizable compound that yields its' ions within water solvent. In terms of acid-base reactions, any salt (any compound that isn't water or carbon dioxide that is a compound of at least two different elements) that dissociates within the water within the products of the reactants.

Alright, I get 1, 2, 3, and 5 now! I did a little more reading on Bronsted-Lowry and Lewis neutralization reactions comparisons/contrasts.

You don't have to answer (4) - that was just me thinking random thoughts that probably don't make sense. Haha

Thanks again guys! 

[rabolisk]

What I think when I think of an aqueous salt: Dissociable/Ionizable compound that yields its' ions within water solvent. In terms of acid-base reactions, any salt (any compound that isn't water or carbon dioxide that is a compound of at least two different elements) that dissociates within the water within the products of the reactants.

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A salt is by definition an ionic compound..Also dissociable and ionizable aren't the same things, and plenty of things other than salts will dissociate in water to produce ions (e.g. any bronsted-lowry acid or base). In a neutralization reaction, you will always get an ionic compound as a product, but this product may or may not be in solid form. If it is dissolved, then it is really just cations and anions in solution. The confusion is whether you call this "aqueous" form of salt a salt, since really there is no interaction between the cations and the anions. They are just solvated by water. But what is true is that in acid-base neutralization reactions, you will have a cation and an anion as a product.

[BetaAmyloid]

You and I are at least thinking the same thing. Wether it be me using the wrong terminology or two different understandings of the same thing, we are on the same page! I understand/agree with your statement.

Thanks!