Lab Experiment for Preparation of Ammonia

[bhuwana65]

Hello ,
We tried to demonstrate preparation of Ammonia by mixing Ammonium Chloride and Calcium Hydroxide in round bottom flask mixed in the proportion of 2:3 .
The flask was in a slanting position with the delivery tube attached to a decicator with Calcium Oxide for drying the gas.
A Flask was attached to the outlet of the decicator for gas collection.

There was no resultant ammonia collected in the collection flask despite a visible flow of gas from the round bottom flask to the decicator on heating.

Need help on identifying the failure of the experiment and suggestions on the rectifications needed to make the experiment sucessful

rgds
Bhuvana
bhuwana65@yahoo.com

 

[Cesium]

You need to heat your solution (you did add water right?) of ammonium chloride and calcium hydroxide. Calcium hydroxide is rather insoluble so it's rather weak at making ammonia, but at near boiling temperatures it should definitely work.

 

[mrjeffy321]

How did you test for the presence of Ammonia in the collection flask?

 

[bhuwana65]

Thanks for your prompt replies .
My replies as below :
1) since water is produced during the reaction I did not add water . If water is to to be added please advice on the proportion to be added.
2) the presence of ammonia was tested using red litmus paper which turned blue initially .

Await your further help.
Regards
Bhuvana

 

[chemisttree]

You need to heat your solution (you did add water right?) of ammonium chloride and calcium hydroxide. Calcium hydroxide is rather insoluble so it's rather weak at making ammonia, but at near boiling temperatures it should definitely work.

Not so. The solubility of lime (calcium hydroxide) decreases as temperature increases. Lime has its highest solubility at near freezing temperature...

 

[chemisttree]

Thanks for your prompt replies .
My replies as below :
1) since water is produced during the reaction I did not add water . If water is to to be added please advice on the proportion to be added.
2) the presence of ammonia was tested using red litmus paper which turned blue initially .

Await your further help.
Regards
Bhuvana

When testing for the presence of ammonia gas, it is best to wet the litmus paper.

You really need to add some water to your experiment. Sugar (sucrose) will aid the solubilization of lime. I would prepare a 10% sucrose solution and add that to the lime. Stir for 5 minutes or so and then add the ammonium chloride. The lime does not need to completely dissolve. I would use a 5:1 ratio of sucrose solution to lime. The amount of ammonium chloride should be 1.5 times the amount of the lime added.

 

[bhuwana65]

Can anybody suggest a site which give details of various quantum numbers and order of filling up the orbitals (for Grade 11 students)
bhuwana
bhuwana65@yahoo.com

 

[Cesium]

Not so. The solubility of lime (calcium hydroxide) decreases as temperature increases. Lime has its highest solubility at near freezing temperature...

This is true, but increasing the temperature to increase the solubility was not my point. It is necessary to increase the temperature in order to increase the rate of reaction. I've performed a similar experiment before using ammonium nitrate and calcium hydroxide and at room temperature you only get a VERY weak smell of ammonia, but near boiling it really starts coming over.

So, bhuwana, I would suggest at least enough water to dissolve the ammonium chloride and to heat your solution. Calcium hydroxide works for producing ammonia but not as easily as more soluble hyroxides like sodium hydroxide.

 

[bhuwana65]

Dear all,
Thanks a lot,my experiment withn ammonia preparation went off suceesfully and i could also perform fountain expt.
bhuwana

 

[chemisttree]

What is the fountain experiment?

 

[mrjeffy321]

What is the fountain experiment?

An exert from the “Golden Book of Chemistry” (1960),
http://i62.photobucket.com/albums/h104/mrjeffy321/PF/AF.jpg

 

[bhuwana65]

For Class XII students ,I am conducting Qualitative salt analysis.While analysing various salt mixtures we had a problem with a particular mixture
It was Leadnitrate+Calcium carbonate.
The mixture does not dissolve in Cold Water/Hot water/Cold dilue Hcl/Hot Dilute Hcl.What i mean we do not get a clear solution to go to Group I,which is lead
In addition to that Lead precipates again In Group IVas lead sulphide in black colour( in presence of NH4cl+in excess of NH4OH+H2S).
It is very confusing.How to guide them .Pl.help
Bhuvana

 

[chemisttree]

Lead is always a problem when you use HCL. The solubility product of lead chloride is 1.6X10^-5 so adding excess HCl to dissolve these will ultimately lead to problems.

Take your cue from the soluble salts of lead, especially nitrate. Try dissolving the calcium carbonate in nitric acid instead.

Good luck.

 

[Sweet&Sour]

Hi
I'm also trying to prepare Ammonia and can you all please just say how you prepare it again I kind of got lost.
Thanks

 

[Ayush Suwal]

uhh can anyone tell answer my question please. why is the mixture of ammonium chloride and calcium hydroxide a paste instead of a solution?

 

[chemisttree]

uhh can anyone tell answer my question please. why is the mixture of ammonium chloride and calcium hydroxide a paste instead of a solution?

Because you didn't add enough water to completely dissolve the solids.

 

[Ayush Suwal]

So u mean to say i got to add more water?

 

[Ayush Suwal]

Because you didn't add enough water to completely dissolve the solids.

but i got a question to answer here "Y IS THE MIXTURE A PASTE INSTEAD OF A solution

 

[chemisttree]

Why is something not in solution? The general answer is that not enough solvent is used.

Why are we using the ingredients as a paste instead of a solution is a different question altogether... Think about the solubility of both ingredients briefly and see if something doesn't come to you.

 

[Ayush Suwal]

Because you didn't add enough water to completely dissolve the solids.

We were given paste instead of solution. The question goes like this "In the preparation of ammonia why is the mixture of ammonia Chloride and Calcium hydroxide a paste NOT a solution." and "Why can't anhydrous calcium chloride be used to dry ammonia"

 

[Ayush Suwal]

i do know about the solubility but we weren't allowed to tamper with it

 

[qionimacawa]

You do not need to have a paste or solution to get ammonia from the two mixtures. In fact as soon as one mixes the two, you could smell the characteristic ammonia vapour coming out. Ammonia. A mixture with two teaspoon fulls will produce enough ammonia for repeating it four times. Just make sure that you use a dry round bottom flask every time. Calcium oxide could be covered in lint and positioned near the mouth of the test tube.

Moisten the red litmus paper and place it near the mouth of the inverted round bottom flask.

For the fountain experiment, the reaction begins by injecting some water into the system and the fountain should always work!

Koroi