An acid -base question

[Ocean5]

Advertisement - Members don't see this ad

There are questions that give you some acid , base name or equation and ask if this is aci or base of Arrhenius, Bronsted or Lewis.

How do we recognize that which one is which one, I know the rules that:
Arrhenius acid produces H+ and ....
However, I 'm not able to apply them. COuld you please help me in application of these definitions? Could you please give me some examples of one which is not the other and vise versa, and why? thanks

 

[jy87]

I just finished writing the DAT a few hours ago...

So off the top of my head:

(note: this is a very general outline)

Arrenhius acid: dissociates in water to produce H ions
" base: dissociates in water to produce OH ions

B-L acid: donates protons
B-L base: accepts protons

The concept of conjugate acids/bases comes into play here.

Lewis Acid: Accepts an electron pair
Lewis Base: Donates an electron pair

Molecules which may not otherwise look like acids or bases can be either of these according to the Lewis definitions so be wary.

If you're studying out of Kaplan or Barron's (I think), their definitions are all you should need to fully grasp the concepts and be able to differentiate between them.

Hope that helps!

 

[Ocean5]

Thanks for your response. I knew the definision. I could apply them. For example it says that:
NAOH is a Arrhenius base. (but why it isn't B base, becasue when it disso. it dissoc. in OH and Na, and OH had a - so it can accept protons or it can be LEWIs base be it can donates E- , but the naswer is just it is ARR base.

What are HCL, NH3, Nh4+ and (ch3)3 N and BF3 , and could you please explainto me why they are just one and not the other ones, whereas Leiws and Bran def is very similar in concept. I really appreciate the fact that you are taking time to answer my question. Thank you

I just finished writing the DAT a few hours ago...

So off the top of my head:

(note: this is a very general outline)

Arrenhius acid: dissociates in water to produce H ions
" base: dissociates in water to produce OH ions

B-L acid: donates protons
B-L base: accepts protons

The concept of conjugate acids/bases comes into play here.

Lewis Acid: Accepts an electron pair
Lewis Base: Donates an electron pair

Molecules which may not otherwise look like acids or bases can be either of these according to the Lewis definitions so be wary.

If you're studying out of Kaplan or Barron's (I think), their definitions are all you should need to fully grasp the concepts and be able to differentiate between them.

Hope that helps!

 

[Blackjack21]

I just memorized the definitions as the other guy posted, and i probably cant explain it any better....but theres are a few things u should memorize:

NH3 is a bronsted-lowry base but doesnt fit the definition of an arrhenius base

BF3 and AlCl3 are lewis acids but dont fit the bronsted lowry acid definition.

Hope that helps

 

[Blackjack21]

My bad...i didnt read ur post all the way through....NH3 is only a bronsted lowry base and not arrenhius b/c an arrhenius follows this: BOH --> B+ +OH- which NH3 doesnt follow (no OH to dissociate).

AlCl3 and BF3 cant be bronsted acids because they dont dissociate into a proton donor.

I hope that helps...i kinda suck at explaning things lol

 

[Ocean5]

My bad...i didnt read ur post all the way through....NH3 is only a bronsted lowry base and not arrenhius b/c an arrhenius follows this: BOH --> B+ +OH- which NH3 doesnt follow (no OH to dissociate).

AlCl3 and BF3 cant be bronsted acids because they dont dissociate into a proton donor.

I hope that helps...i kinda suck at explaning things lol

You are being modest. You explained it great, I thank you very much for your help. You enlightened me a big time. Thank you.