Determining Anions & Cations! (1 Viewer)

[louielouiee]

I need to make a flowchart for an assesment coming up, can anybody help? We're given an unknown solution and have to run through a series of tests.
Also, could you be very specific as to what solutions to add/acidify with?

For example, instead of saying "add Cl^- and it will precipitate" could you say "add NaCl₂ and it will precipitate."

Thanks!

 

[nightweaver066]

You could say "Add Cl- (in the form of NaCl) for a white precipitate" although i wouldn't know the marking guidelines so its best to ask your teacher.

 

[louielouiee]

Guidelines are pretty much just conducting the experiment correctly in class and being specific with which solutions you add.

 

[golgo13]

I believe your best port of call is Conquering Chem, if you have it, the book basically outlines the process you are looking for, hope that helps

 

[louielouiee]

That's my chem book, i don't really like it that much! I found what you mean though. What does it mean by 'filtrate' inbetween tests?

 

[golgo13]

After confirming the presence of the cation/anion in the order given you need to precipitate it out as other tests following it will be affected, as tests following it will also react with previous cations/anione (earlier on in the hierarchy)

So you are looking for the presence of lead, that is the first one they test for from memory, if you don't remove lead. Lead will react with every test following it

Hope that helps

 

[louielouiee]

Is that just adding in excess?

 

[golgo13]

Excess is part of it but you have to remove the cation and anion once you identify it's presence, do this by precipitating and filtering it

 

[louielouiee]

Just curious..
If you do identify the cation/anion, can you just get a new aqueous sample and continue testing for others? Instead of filtering.

 

[golgo13]

Nope
referring to my previous post you have to remove it.
You know that there's a certain order to doing the test yes?
That order is there because the test following the previous one WILL react with the tests you are going to do later, thus skewing your results, so you can't tell if it really have copper (lets say) when it initially reacts with Cl (test for lead),

 

[Alkenes]

Use Jacaranda ....it had got mad tables

 

[Alkenes]

Guys do we need to know how AAS work....like detailed working??

 

[Alkenes]

bump

 

[Ms106]

I think we only need to have a general knowledge about the workings, eg Why certain wavelengths are chosen, how the process works, etc
Also how to do calibration curves and calculate absorption.

 

[iSplicer]

Guys do we need to know how AAS work....like detailed working??

Yes.