[lachie123]

Hello all Please could someone Help.

I have a Labritoty test tomorow and Have apsolutly no idea what to do ,

it is about

DETERMINATION of % of NaCl by mass in Na2CO3/NaCl  mixture by titration .
I will have  0.2M HCL at my disposeal but have know idea what to do with it alll
PLEASE HELP I HAve my test in less then 24 hours and if i do not pass this test i will fail the subject totally  plaz any help at all  would be apreasiated THANKYOU in advance

[Borek]

Hint number 1: please read forum rules.

Hint number 2: use spellchecker before posting.

Hint number 3: HCl can be used to determine amount of carbonate in the mixture.

[lachie123]

Im sorry that i did not use spell check. You said that i can use the HCl to find the ammount of carbonate in the mixture , please could you tell me more , I have honestly looked though everybook in the school libary to try to find any help, but had no luck .I would be extrea,ly greatful if i could have some more light shed on the subject.
Thanks Lachie.

[Alberto_Kravina]

...always start by writing a balanced chemical equation...

[lachie123]

I thought about about that but did not know how for this particular instance.

[Borek]

30 seconds googling for carbonate titration:

http://www.cofc.edu/~kinard/221LCHEM/CHEM221L%20Titrimetric%20Sodium%20Carbonate.htm

Once you know amount of carbonate, NaCl is the rest.

[lachie123]

Thankyou so so much

[lachie123]

This dosn't seem right , I am trying to find the percentage by mass of Nacl not Na2CO3
would the site info be similer or do i need to try to find a different site.

[Borek]

Read last phrase of my previous message.

[Alberto_Kravina]

You could always perform Mohr/Fajans/Vollhard method if you want to determine the content of NaCl in a different way, however, Borek´s idea is much better (and faster)

[lachie123]

Im sorry but still it is not exactly clear to me , could a little more help be posssible.please.



Is the Mohr/Fajans/Vollhard method also titration.

[Borek]

Im sorry but still it is not exactly clear to me , could a little more help be posssible.please.

You start weighting sample, then you determine mass of sodium carbonate, then you substract mass of sodium carbonate from the sample mass - and you have mass of sodium chloride.

Is the Mohr/Fajans/Vollhard method also titration.

Yes.

[lachie123]

how do i weigh the sample if it is a solution form

[lachie123]

just so you know what i have to find , the results required are .mixture indentification , mass of mixture, Dissolved mixture volume made up to ,  aliquot volume used
indicator used.

[Borek]

Are you sure your mixture will come already dissolved? Not as a solid mixture? If so, HCl solution will not be enough to determine composition. You will be either given a solid mixture that you can weight before dissolving, or - if you are given solution of carbonate and chloride - you must have more reagents available.