Ion Exchange Column

[sanalicious]

speak up dude :D

[stevoh92]

@crharrison. Cheers! thanks alot for your help!

[stevoh92]

Hi, just a quick question. I am trying to use an cation exchange to determine the concentation of a copper sulphate soloution (approx. 0.2M) by exchangeing the copper ions for hydrogen ions then titrateing the effluent against a standard NaOH soloution and i was wondering what strength base to use to detemine wether or not the effluent is neutral in the drop test and what stength acid to use to regenerate the resin?

Thanks

[crharrison]

@stevoh92 For this lab we have the students regenerate the column with 3 M HCl. The titrant used is 0.1 M NaOH. I would suggest using about the same concentrations, as if your titrant is too strong it will yield a false positive in the drop test and make reaching an accurate endpoint in the titration much more difficult.

[rsty615]

Thanks for all your help! Regarding the pH probe, the acid is around 0.5M, which is typically beyond the (accurate) range of standard electrodes. I actually went ahead and titrated the metal solution; it gave me a good looking equivalence point but after that the curve started to look funky (i assume metal interference). Either way, the result was 0.419M, where as the original acid was ~0.6M. I'm also going to run the metal thru a column just to see if I can get a reasonable number. Thanks again

[rsty615]

I have a solution of a metal dissolved in perchloric acid and I want to be able to determine the free acid concentration of that solution. Could I use a cation exchange resin to elute the free H+ and then titrate it with NaOH?

[crharrison]

@rsty615 No, the metal cations will also exchange on the column yielding even more protons. The best way to determine the free acid may be to do a simple acid/base titration on a fraction of your sample.

[rsty615]

@crharrison It's true. But could one correct for the total acid liberated by the metal (3+)?

[crharrison]

@rsty615 You could account for the acid due to the ion exchange of the metal, but you must obviously know the exact amount of metal, and that all the metal is in the same oxidation state. Plus, any additional salts in the solution will increase the amount of acid coming off the column.

[rsty615]

@crharrison I ask because doing a simple acid/base titration of my metal solution would most likely result in the hydrolysis and eventually the precipitation of the metal ( pH > 6).

[crharrison]

@rsty615 I think we have both been over thinking this problem, as there would seem to be a very simple solution to the problem, use a pH meter; the pH is a measure of the concentration of free H+ after all.

However, if you must do a titration, the pH will not likely exceed 6 until you reach the equivalence point so only a minimal amount of precipitation might occur. And at that point it is unlikely to interfere with the measurement.

[MrPavan1984]

fantastic

[MetaIhead89]

good video