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Topic: Why does the reaction between HCl + NH3 happen?  (Read 9515 times)

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Offline gleeman

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Why does the reaction between HCl + NH3 happen?
« on: July 19, 2007, 09:28:16 AM »
Why does the reaction between HCl + NH3 happen?

I know that HCl is ionic and NH3 is non-polar because of symmetry. So has NH3 ionic properties? If has, can this be the reason why the reaction happen?

I appreciate your guidance

Offline vladi307

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Re: Why does the reaction between HCl + NH3 happen?
« Reply #1 on: July 19, 2007, 09:39:43 AM »
NH3 is soluble in the water? What are you thiniking about it?

Offline gleeman

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Re: Why does the reaction between HCl + NH3 happen?
« Reply #2 on: July 19, 2007, 11:11:02 AM »
NH3 is soluble in the water? What are you thiniking about it?
Yes,
I am thinking why does the following reaction happen:
HCl + NH3 => NH4Cl

Is the main reason that HCl donates proton for NH3 which then turn out ammonium? As a result, Cl- forms salmiac  (NH4Cl) with the product (ammonium).

Could you tell me, is this latter the right reason?

Thanks for your reply!
« Last Edit: July 19, 2007, 02:44:44 PM by gleeman »

Offline Erichsen

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Re: Why does the reaction between HCl + NH3 happen?
« Reply #3 on: July 20, 2007, 08:56:20 AM »
The reaction happens because delta G < 0.

delta G = delta H - T * delta S

When acid and bases are mixed they usually develop heat (exoterm), which means a negative delta H.
Delta S are a measure of the dissorder of the system. When NH4Cl is formed (salt) the system become more ordered (lattice), which means delta S become negative. But delta H must be more negative then T * delta S.
Hope this helps.

Another way to think about is, HCl is a strong acid, that reacts with almost every bases (NH3 is a weak base, due to its free electronpair, which can accept the hydrogen-ion from HCl ).

Offline gleeman

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Re: Why does the reaction between HCl + NH3 happen?
« Reply #4 on: July 20, 2007, 09:24:16 AM »
The reaction happens because delta G < 0.

delta G = delta H - T * delta S

When acid and bases are mixed they usually develop heat (exoterm), which means a negative delta H.
Delta S are a measure of the dissorder of the system. When NH4Cl is formed (salt) the system become more ordered (lattice), which means delta S become negative. But delta H must be more negative then T * delta S.
Hope this helps.

Another way to think about is, HCl is a strong acid, that reacts with almost every bases (NH3 is a weak base, due to its free electronpair, which can accept the hydrogen-ion from HCl ).

Thanks a lot!
I really appreciate your guidance!
Both of the ways you illustrated me were the ones I was thinking - I was unable to illustrate them on paper but luckily you managed - thank you!

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