Im testing for harness of bottled water samples. I add 1ml of ammonia to 10ml of the water then heat the water untill condensation forms on the rim. Then i add the calmagite indicator but when i titrate with the edta the most it ever takes is 3-4 ml to turn dark blue.
@thetrueturnip That's not too surprising, given how low the concentration of calcium is likely to be in bottled water. If you are looking to improve your accuracy you might want to try titrating larger samples of bottled water (e.g. 100 mL) or diluting your EDTA (10 fold dilution). This way you may be able to get some better differentiation between sampels; as the concern with titrating a simple with too little solution is the chance of overshooting the endpoint is much higher.
@anahmar89 Une de mes amies au Faculte Saint Jean a l'Universite d'Alberta etait en trains de les traduir, je ne sais pas si elle les a finis a ce point. Je m'excuse pour ne pas les traduire moi-meme, mais j'ai jamais appris la vocabulaire scientific en Francais.
Ok thanks :) for lead, since it's colorless, shall I use erichrome black T to color it first? Should I do direct or back titration? If you do come across any link could you please share it here?(for lead) thank you!!
@superdenj The analysis should work for lead and many other metals. There are however, some considerations that need to be taken with respect various aspects of the analysis (e.g. pH, indicator, use of magnesium...). You should be able to find a procedure on-line relatively easily. So to answer your question, the analysis with EDTA as a titrant would work, though this exact procedure may need some modification.
@leytonhewit1 Sorry for the delay in getting back to you. This analysis might work for clear juices (e.g. apple) but there are a few things you will need to consider in the analysis:
- presence of other salt cations interacting with EDTA (e.g. Na, Fe...)
- citric acid and some proteins can interfere with the complexation of cations with EDTA
-the pH needs to be adjusted prior to the analysis
It's worth a try, though you may want to use a standard addition method for accuracy of the analysis.
@rockindxb1 This titration method could be used for the measurement of water hardness. Hard water is typically due to the presence of calcium and magnesium ions (and some other trace metal ions). All these metal ions can be complexed by EDTA; in 1:1 complexes. So the total number of moles of metal ions can be determined. This won't give you the typical water hardness units (mg/mL), or specifics on which metal ions are present, unless you assume the only one type of metal ion is present.
@fabulousmango slightly larger amounts of magnesium in the titrant shouldn't impact the titration; the complexation factor for EDTA:Calcium is about 1000x greater than EDTA:Magnesium. So unless you have grossly too much magnesium you shouldn't impact the endpoint. There may be some impact on the color, as that is the result of the indicator complexing with free metal; having more magnesium to complex with might alter how clear the color change is.
Too concentrated EDTA will cause higher deviation from true results, as the activity in the solution grows with concentration. This means the more ions there are in solution, the more will will they be affected by each other, which results in a seemingly smaller amount of dissociation than actually happening.
@22fause21 No, the water, so long as it is free of any metals, will not have any impact on the titration. Pure water can be added to most aqueous titrations with no consequences as titrations are not concentration dependent.
@qrais Your ability to get very accurate results may decrease. This is because every drop of titrant will contain larger amounts of EDTA the last drop required to make the colour change may contain far more EDTA than necessary. But otherwise there is no detriment to using higher concentrations of EDTA.
@crharrison thank you so much for your replay. Is it possible that too concentrated EDTA kills the buffer solution and the pH raises, causing the reaction to stop or reverse?
@idiotkrati I'm not certain, it would really depend on how low the pH of the EDTA solution was (and that depends on what form of EDTA you are using). One way to overcome that would be to use a higher concentration of buffer to mitigate the pH changes should they be occurring.
@CelestialPlatypus Yes. Otherwise the students become overstimulated and cannot focus on their work properly ;-)
The reality is that's just what happens to my voice through multiple takes while trying to narrate a video at a steady pace, clearly and without stumbling over my words. Perhaps I'll try to liven my voice up a bit more in future recordings, but from what I can tell, I'm not nearly as monotone in my lectures.
We used something called HSNNA as an indicator when measuring the mass of the calsium. The we added some hydrogen peroxcide and removed the blue colour. And after that we used Erio T as an indicator when measuring the mass of magnesium. PH was above 10 the whole time (except when removing the sedimented calsium with hydrogen chloride)
The conc of EDTA has to be very small indeed before it will work. If using the powder, then place a tiny amount (almost invisible amount) of powder into the flask before titration after the buffer.
it was a mixture of Ca\Mg sample using the total end point and subtract the Ca from it to get the Mg ofcourse we made the Mg ppt and the second time..but ya..it was coool and i do see these colors..
That's unfortunate that it did not work. One reason the experiment can fail is if the pH of the solution is not correct for the indicator and EDTA. With this experiment the pH ideally should be between 9 and 10, a pH below this will likely cause the analysis to fail.
Well, we did use a buffer of pH 10, but its possible the EDTA concentration was insufficient for our sample. I suppose I'll have a better take on that after I do the concentration calculations for the EDTA against our calcium standard.
Im testing for harness of bottled water samples. I add 1ml of ammonia to 10ml of the water then heat the water untill condensation forms on the rim. Then i add the calmagite indicator but when i titrate with the edta the most it ever takes is 3-4 ml to turn dark blue.
thetrueturnip 1 month ago
@thetrueturnip That's not too surprising, given how low the concentration of calcium is likely to be in bottled water. If you are looking to improve your accuracy you might want to try titrating larger samples of bottled water (e.g. 100 mL) or diluting your EDTA (10 fold dilution). This way you may be able to get some better differentiation between sampels; as the concern with titrating a simple with too little solution is the chance of overshooting the endpoint is much higher.
crharrison 4 weeks ago
Si quelqu'un peut m'expliquer la manipulation en français ?
anahmar89 1 month ago
@anahmar89 Une de mes amies au Faculte Saint Jean a l'Universite d'Alberta etait en trains de les traduir, je ne sais pas si elle les a finis a ce point. Je m'excuse pour ne pas les traduire moi-meme, mais j'ai jamais appris la vocabulaire scientific en Francais.
crharrison 4 weeks ago
Ok thanks :) for lead, since it's colorless, shall I use erichrome black T to color it first? Should I do direct or back titration? If you do come across any link could you please share it here?(for lead) thank you!!
superdenj 3 months ago
@superdenj I don't believe that one can post links through the comments, so just google the following: edta, lead, titration
Good luck.
crharrison 3 months ago
Can I know, does this work for lead?
superdenj 3 months ago
@superdenj The analysis should work for lead and many other metals. There are however, some considerations that need to be taken with respect various aspects of the analysis (e.g. pH, indicator, use of magnesium...). You should be able to find a procedure on-line relatively easily. So to answer your question, the analysis with EDTA as a titrant would work, though this exact procedure may need some modification.
crharrison 3 months ago
can u make a video about the concentration of calcium ions in juice
leytonhewit1 4 months ago
@leytonhewit1 Sorry for the delay in getting back to you. This analysis might work for clear juices (e.g. apple) but there are a few things you will need to consider in the analysis:
- presence of other salt cations interacting with EDTA (e.g. Na, Fe...)
- citric acid and some proteins can interfere with the complexation of cations with EDTA
-the pH needs to be adjusted prior to the analysis
It's worth a try, though you may want to use a standard addition method for accuracy of the analysis.
crharrison 4 months ago
Can it be used for the analysis of the hardness of water? If yes how can we determine it?
rockindxb1 7 months ago
@rockindxb1 This titration method could be used for the measurement of water hardness. Hard water is typically due to the presence of calcium and magnesium ions (and some other trace metal ions). All these metal ions can be complexed by EDTA; in 1:1 complexes. So the total number of moles of metal ions can be determined. This won't give you the typical water hardness units (mg/mL), or specifics on which metal ions are present, unless you assume the only one type of metal ion is present.
crharrison 7 months ago
What would happen if too much magnesium chloride hexahydrate was added? Would the endpoint be pushed back?
fabulousmango 8 months ago
@fabulousmango slightly larger amounts of magnesium in the titrant shouldn't impact the titration; the complexation factor for EDTA:Calcium is about 1000x greater than EDTA:Magnesium. So unless you have grossly too much magnesium you shouldn't impact the endpoint. There may be some impact on the color, as that is the result of the indicator complexing with free metal; having more magnesium to complex with might alter how clear the color change is.
crharrison 8 months ago
Too concentrated EDTA will cause higher deviation from true results, as the activity in the solution grows with concentration. This means the more ions there are in solution, the more will will they be affected by each other, which results in a seemingly smaller amount of dissociation than actually happening.
Shoryukenish 9 months ago
Thank you for your kind reply. I never did that in any experiment we've done thinking it can affect the results.
invalidusername804 10 months ago
Hi, I saw in this experiment that you are rinsing the sides of the flask with water. Does that in any sense, affect the titration?
22fause21 10 months ago
@22fause21 No, the water, so long as it is free of any metals, will not have any impact on the titration. Pure water can be added to most aqueous titrations with no consequences as titrations are not concentration dependent.
crharrison 10 months ago
What happens if you use too concentrated EDTA?
qrais 10 months ago
@qrais Your ability to get very accurate results may decrease. This is because every drop of titrant will contain larger amounts of EDTA the last drop required to make the colour change may contain far more EDTA than necessary. But otherwise there is no detriment to using higher concentrations of EDTA.
crharrison 10 months ago
@crharrison thank you so much for your replay. Is it possible that too concentrated EDTA kills the buffer solution and the pH raises, causing the reaction to stop or reverse?
idiotkrati 10 months ago
@idiotkrati I'm not certain, it would really depend on how low the pH of the EDTA solution was (and that depends on what form of EDTA you are using). One way to overcome that would be to use a higher concentration of buffer to mitigate the pH changes should they be occurring.
crharrison 10 months ago
@CelestialPlatypus Yes. Otherwise the students become overstimulated and cannot focus on their work properly ;-)
The reality is that's just what happens to my voice through multiple takes while trying to narrate a video at a steady pace, clearly and without stumbling over my words. Perhaps I'll try to liven my voice up a bit more in future recordings, but from what I can tell, I'm not nearly as monotone in my lectures.
crharrison 11 months ago
Insaaaaaaneeeee!!!! :D
L4s4gn3 11 months ago
You should just put that flask on a stir plate and drop a stir bar, for convenience lol.
laffoutlouds 1 year ago
We used something called HSNNA as an indicator when measuring the mass of the calsium. The we added some hydrogen peroxcide and removed the blue colour. And after that we used Erio T as an indicator when measuring the mass of magnesium. PH was above 10 the whole time (except when removing the sedimented calsium with hydrogen chloride)
mutzilnosoundl 1 year ago
Hahaa I did this last thursday and went fine :) Maybe too much indicator though, but titration was succescful!
mutzilnosoundl 1 year ago
The conc of EDTA has to be very small indeed before it will work. If using the powder, then place a tiny amount (almost invisible amount) of powder into the flask before titration after the buffer.
fergalmj 1 year ago
I've just did this todaaaaaaaaay..!!!
it was a mixture of Ca\Mg sample using the total end point and subtract the Ca from it to get the Mg ofcourse we made the Mg ppt and the second time..but ya..it was coool and i do see these colors..
Drgeius2009 1 year ago
stir bar!
rsty615 2 years ago
^_^
8Dmeow 2 years ago
I did that experiment yesterday and could NOT get the darn thing to work!
medic007 2 years ago
That's unfortunate that it did not work. One reason the experiment can fail is if the pH of the solution is not correct for the indicator and EDTA. With this experiment the pH ideally should be between 9 and 10, a pH below this will likely cause the analysis to fail.
crharrison 2 years ago
Well, we did use a buffer of pH 10, but its possible the EDTA concentration was insufficient for our sample. I suppose I'll have a better take on that after I do the concentration calculations for the EDTA against our calcium standard.
medic007 2 years ago
@crharrison
ya we used Buffer to stablize the pH it was the EBT for the total and then Muroxide selective for the Ca..
Drgeius2009 1 year ago