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Topic: Ammonia and hydrochloric acid  (Read 2030 times)

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Offline Md.Sakib Shahriar

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Ammonia and hydrochloric acid
« on: April 19, 2021, 07:02:58 PM »
Why hydrochloric acid is a lewis acid and ammonia a lewis base?

Is it because that the electronegativity of Cl and N might be equal but their size aren't? So charge density differs a lot moreover size difference between chlorine and hydrogen  is much more compared to that of nitrogen and hydrogen. That is why HCl tends more to releaseproton than donating lone pair electrons whereas the opposite case is observed in case on ammonia. Could it be the reason?
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Offline Orcio_87

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Re: Ammonia and hydrochloric acid
« Reply #1 on: April 20, 2021, 05:01:09 AM »
HCl:

H+ + H2O ---> H3O+ (Lewis acid)

CH3-CH2-CH+-CH3 + Cl- ---> CH3-CH2-CHCl-CH3 (Lewis base)

NH3:

H+ + NH3 ---> NH4+ (Lewis base)
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Offline chenbeier

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Re: Ammonia and hydrochloric acid
« Reply #2 on: April 20, 2021, 05:41:56 AM »
What you wrote is in my opinion the Brönstedt concept.
Brönstedt acid donate H+, Brönstedt base accept H+


Lewis concept dials with elektronpair

Lewis acid accept electron pair

Example BF3 + F- => BF4-

BF3 is the acid, which can accept one electronpair from flouride

Lewis base donate electron pair

Like NH3 + H+ => NH4+, the base is ammonia not ammonium, because ammonia donate the electronpair to H+.
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Offline Orcio_87

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Re: Ammonia and hydrochloric acid
« Reply #3 on: April 20, 2021, 05:49:55 AM »
Quote
What you wrote is in my opinion the Brönstedt concept.
Brönstedt acid donate H+, Brönstedt base accept H+

CH3-CH2-CH+-CH3 + Cl- ---> CH3-CH2-CHCl-CH3 (Lewis base)

Where do you see addition of H+ to Cl-, if this reaction rely on creation of C-Cl bond ???

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Like NH3 + H+ => NH4+, the base is ammonia not ammonium, because ammonia donate the electronpair to H+.
You're right, I didn't think that someone could have problems with reading.

Words "Lewis acid", "Lewis base" means examples of reaction where HCl or NH3 can act as Lewis base or acid (HCl is source of Lewis acid and Lewis base).
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Offline Md.Sakib Shahriar

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Re: Ammonia and hydrochloric acid
« Reply #4 on: April 20, 2021, 05:59:56 AM »
Both of these compound are polar and do have lone pair electrons. So what is making these two compounds different based on nature(acidic/basic)?
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Offline chenbeier

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Re: Ammonia and hydrochloric acid
« Reply #5 on: April 20, 2021, 06:00:14 AM »
The 2-Butyl cathion is the Lewis acid  can accept electron pair and the Chloride is the Lewis base which donate one electron pair. The product 2-chlorobutane is nothing of them.
HCl  itself is also nothing of them. Only in water reaction takes place where water is the Lewis base donate electron  pair to H+ , which is in this case is also Lewis acid to get H3O+

Quote
Words "Lewis acid", "Lewis base" means examples of reaction where HCl or NH3 can act as Lewis base or acid

This sentences I dont agree
.
The process is also a kind of neutralization.  A Lewis acid react with a Lewis base to form a new product.
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Offline chenbeier

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Re: Ammonia and hydrochloric acid
« Reply #6 on: April 20, 2021, 06:07:55 AM »
Quote from: Md.Sakib Shahriar on April 20, 2021, 05:59:56 AM
Both of these compound are polar and do have lone pair electrons. So what is making these two compounds different based on nature(acidic/basic)?

The defintions are clear

Electron pair acceptors are acids according Lewis.
Electron pair donators are base according Lewis.
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Offline Md.Sakib Shahriar

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Re: Ammonia and hydrochloric acid
« Reply #7 on: April 20, 2021, 06:18:59 AM »
Quote from: chenbeier on April 20, 2021, 06:07:55 AM
Quote from: Md.Sakib Shahriar on April 20, 2021, 05:59:56 AM
Both of these compound are polar and do have lone pair electrons. So what is making these two compounds different based on nature(acidic/basic)?

The defintions are clear

Electron pair acceptors are acids according Lewis.
Electron pair donators are base according Lewis.
So these are considered acid and base based on observation rather than the conceptual approach of presence of polar bonds and lone pair electrons. Right?
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Offline Orcio_87

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Re: Ammonia and hydrochloric acid
« Reply #8 on: April 20, 2021, 06:25:46 AM »
Quote
HCl  itself is also nothing of them. Only in water reaction takes place where water is the Lewis base donate electron  pair to H+ , which is in this case is also Lewis acid to get H3O+
I think that HCl can be a Lewis acid as a whole since (in reaction in water) accepting lone pair from H2O will led to disruption of H-Cl bond and production of H3O+ and Cl-.
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This sentences I dont agree
.
The process is also a kind of neutralzation.  A Lewis acid react with a Lewis base to form anew product
Then with what you disagree if H+, Cl- and NH3 are writed on the side of the reagents?
« Last Edit: April 20, 2021, 08:34:41 AM by Orcio_Dojek »
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Offline chenbeier

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Re: Ammonia and hydrochloric acid
« Reply #9 on: April 20, 2021, 06:58:34 AM »
 You erased the major point

Quote
Words "Lewis acid", "Lewis base" means examples of reaction where HCl or NH3 can act as Lewis base or acid

You saying the acid or base is the whole process , but it isnt . The compound can be acid or base.
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Offline Orcio_87

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Re: Ammonia and hydrochloric acid
« Reply #10 on: April 20, 2021, 07:05:08 AM »
@chenbeier

What do you mean by "whole process"?

HCl can act like source of H+ (Lewis acid), Cl- (Lewis base) and that is why I posted reactions with H2O and CH3-CH2-CH+-CH3.

NH3 can be only Lewis base.
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Offline chenbeier

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Re: Ammonia and hydrochloric acid
« Reply #11 on: April 20, 2021, 08:42:36 AM »
Quote
Words "Lewis acid", "Lewis base" means examples of reaction...

You talking about the whole process that an acid react with a base.
But the Lewis acid or base  can only be a compound not a reaction.
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Offline Orcio_87

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Re: Ammonia and hydrochloric acid
« Reply #12 on: April 20, 2021, 09:18:23 AM »
Lewis acid or base is a compound, but its properties need to be verified by some reaction.

For example:

NH3 + H2O ---> NH4+ + OH- (NH3 is base, H2O is acid)

NH3 + H2O ---> NH2- + H3O+ (NH3 is acid, H2O is base)

Both compounds have lone electrons, but only first reaction takes place, so we could say that NH3 (in this case!) is stronger Lewis base than H2O.
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Offline chenbeier

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Re: Ammonia and hydrochloric acid
« Reply #13 on: April 20, 2021, 09:51:38 AM »
Nobody that is wrong and now you also talking about compounds.
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Offline Orcio_87

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Re: Ammonia and hydrochloric acid
« Reply #14 on: April 20, 2021, 10:04:03 AM »
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Nobody that is wrong and now you also talking about compounds.

But isn't true that you also linked compounds with reactions ?
Quote
Lewis concept dials with elektronpair

Lewis acid accept electron pair

Example BF3 + F- => BF4-

BF3 is the acid, which can accept one electronpair from flouride

Lewis base donate electron pair

Like NH3 + H+ => NH4+, the base is ammonia

?
« Last Edit: April 20, 2021, 01:30:43 PM by Orcio_Dojek »
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