Evolution of ammonia in cases

[Gourab_chill]

Homework Statement

I have given a number of compounds and asked which of them liberate ammonia when rected with NH4Cl( see the attachment for the complete question)

Relevant Equations

no equations probably

I don't really have any idea how to approach this, but the answer says that it is the compounds which are more basic than ammonia liberate it.

 

[Borek]

I am afraid It is all in the reaction equations.

First things first: can you write reaction equation for NH₄Cl with NaOH? While NaOH is not present on the list, it is exactly type of the reaction that is important here.

 

[Gourab_chill]

I am afraid It is all in the reaction equations.

First things first: can you write reaction equation for NH₄Cl with NaOH? While NaOH is not present on the list, it is exactly type of the reaction that is important here.

Well the reaction is NH4Cl + NaOH --> NaCl + H2O + NH3

But what has NaOH to do with it?

 

[sysprog]

Well the reaction is NH4Cl + NaOH --> NaCl + H2O + NH3

But what has NaOH to do with it?

It's for illustrational purposes, and you seem to me to have grasped the concept, without realizing that @Borek's point was for you to grasp the concept.

 

[Borek]

Now that you know what is the idea behind, can you think which of the substances listed will react with the NH₄Cl to produce ammonia?

 

[Gourab_chill]

Now that you know what is the idea behind, can you think which of the substances listed will react with the NH₄Cl to produce ammonia?

I would guess NaNH2 as Nh2- is a stong base like NaOH?
I'm not quite sure - i cannot understand the basic idea behind this question.

 

[Borek]

Is the NaNH₂ the only base between the substances given?

How strong has the base be to steal H⁺ from NH₄⁺?

 

[Gourab_chill]

No except urea all the other are bases, some strong and some weak.
Well I don't have much of a idea on how much strong the base has to be in order to abstract a proton from NH4+

 

[Borek]

Think this way: when two bases compete for a proton, which one will win - the stronger one, or the weaker one?

 

[Gourab_chill]

the stronger one but how should I know which one is strong enough to react?

 

[Borek]

That's what the question is about - and the only sure way to check is to look in the tables. There are some general rules though saying what to expect from different nitrogen atoms in different functional groups. My bet is that your textbook should contain them, if not, try to google for Ka tables of organic compounds (sorry, can't be more specific at the moment).