I was wondering is there anyone that can link me to a paper about lead titration from nitric solution?
Lead & Nitric Solution
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Martijn
Well-known member
Add small amounts of sulfuric acid, this will push out any lead as insoluble lead sulfate.
Thank you very very much sir.
Just to re-hash this conversation. If a solution is just made up of lead/silver nitrate. If you add small amounts of sulfuric acid.
Will it precipitate silver sulfate? Or just lead sulfate?
Will it precipitate silver sulfate? Or just lead sulfate?
From the start it preferentially precipitates lead, as lead sulfate is much more insoluble than silver sulfate. But i am worried about the endpoint recognition, as both compounds are white.
Considering the robustness of lead precipitation from the solution... If you know roughly how much lead you have, you can directly add molar equivalent of sulfuric acid to it. Stirr and wait to precipitate and settle properly. After decanting the solution, add bit more sulfuric, but just a tiny bit, and observe. Silver sulfate has some solubility (I think like 8g/L), and there should be a clear gap between ending PbSO4 precipitation and starting Ag2SO4 precipitation.
Additionally, you can grab the filtered residue and try to dissolve it in hot water or hot aqueous sulfuric acid. After the solids fall to the bottom, test the liquid with drop of NaCl solution - if you precipitated any Ag2SO4, you will clearly see formation of AgCl.
Just be aware that AgCl test is extremely sensitive, and you probably get some reaction from the precipitate, as it is hard to wash 100%. Just milkiness isn´t very concerning. If you get quark-like precipitate, you overshooted with sulfuric in lead precipitation.
If you just want to separate lead and silver from nitrate solution, cement silver on copper instead. Much easier.
If the ammount of lead is not very big, you can salt the AgCl out carefuly, trying not to overshoot the ammount. Similar to the Ag2SO4 issue - AgCl is completely insoluble in the solution, but PbCl2 is sparingly soluble. So you will be able to slowly "titrate" the ammount of NaCl solution (or HCl) needed. To the end of the AgCl precipitation, you will get only milky white solution, not the actual heavy precipitate. That would be your endpoint.
*Edit
Kurtak mentioned much more effective and easy way how to accomplish the separation of PbCl2/AgCl below. Forget about this maybe working, but certainly lenghty and uncertain nonsense, which my coffee-deprived brain worked out in the morning
Considering the robustness of lead precipitation from the solution... If you know roughly how much lead you have, you can directly add molar equivalent of sulfuric acid to it. Stirr and wait to precipitate and settle properly. After decanting the solution, add bit more sulfuric, but just a tiny bit, and observe. Silver sulfate has some solubility (I think like 8g/L), and there should be a clear gap between ending PbSO4 precipitation and starting Ag2SO4 precipitation.
Additionally, you can grab the filtered residue and try to dissolve it in hot water or hot aqueous sulfuric acid. After the solids fall to the bottom, test the liquid with drop of NaCl solution - if you precipitated any Ag2SO4, you will clearly see formation of AgCl.
Just be aware that AgCl test is extremely sensitive, and you probably get some reaction from the precipitate, as it is hard to wash 100%. Just milkiness isn´t very concerning. If you get quark-like precipitate, you overshooted with sulfuric in lead precipitation.
If you just want to separate lead and silver from nitrate solution, cement silver on copper instead. Much easier.
If the ammount of lead is not very big, you can salt the AgCl out carefuly, trying not to overshoot the ammount. Similar to the Ag2SO4 issue - AgCl is completely insoluble in the solution, but PbCl2 is sparingly soluble. So you will be able to slowly "titrate" the ammount of NaCl solution (or HCl) needed. To the end of the AgCl precipitation, you will get only milky white solution, not the actual heavy precipitate. That would be your endpoint.
*Edit
Kurtak mentioned much more effective and easy way how to accomplish the separation of PbCl2/AgCl below. Forget about this maybe working, but certainly lenghty and uncertain nonsense, which my coffee-deprived brain worked out in the morning
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Orvi really appreciate the insight. You are right on the money. I am an engineer not a chemist. I had silver and lead from lead extraction using fire assays. I had it all dissolved in solution. Precipitated both lead and silver chloride together. Went to melt it in a furnace. Found out through research lead and silver both precipitate using HCI. I am away of the reactive series of metal. I am going to try both ways now that I know to be honest.
Thank you both!
Thank you both!
kurtak
Well-known member
Per the bold print - true if talking about cold water - however - PbCl2 is VERY soluble in HOT water
Therefore - if you precipitate both AgCl & PbCl with HCl or salt you can wash (dissolve) the PbCl out by putting the AgCl/PbCl through several HOT water washes - The PbCl will dissolve in the HOT water & then will precipitate back out (from the decanted HOT water wash) when it cools
So - there are two ways to tell when you have washed all the PbCl out of the AgCl
First is - after each HOT water wash - pour that wash (at least a small sample of that wash) in a jar (small so it cools faster) & if after cooling a white cloud appears you still have lead in the AgCl
Then - AgCl photo changes when exposed to light (turns purple/gray) - PbCl does not photo change (stays white) --- so if you put/pour some of the chlorides in a jar - put it in the sun (or any light - but sun is very quick) & you see white specks that don't photo change - you still have PbCl in with the AgCl - need more hot water washing
Oppps - one more test - the smear test - AgCl will actually break apart when pressure is applied PbCl will actually smear
Washing the PbCl out of AgCl is actually quite easy - Boil the water first - then ad the (boiling) HOT water to the chlorides - the hot water will dissolve the PbCl & as well the hot water will cause the AgCl to aggregate into large AgCl particles that settle fairly quickly allowing you to decant the dissolved PbCl while the water is still hot repeating the hot water washes until the above tests show you have separated the lead from the silver
Kurt
Example; - if you have the white (PbCl) specks after the photo change test - & you take a stir rod & press a white speck against the side of the jar - it will smear on the jar surface whereas the AgCl wont
Sometimes my brain do not function properly in the morning
you are absolutely right. Hot wash accomplish the thing.kurtak
Well-known member
LOL - the older I get the more coffee it takes to get rid of the morning brain fog - LOLSometimes my brain do not function properly in the morning
Kurt
Aah so that is what is.LOL - the older I get the more coffee it takes to get rid of the morning brain fog - LOL
Kurt
I’m fearing if I’m beyond the help of coffee now.
Just throw myself into the volcano
Per-Ove
kurtak
Well-known member
Aah so that is what is.
I’m fearing if I’m beyond the help of coffee now.
Just throw myself into the volcano
Per-Ove
Now you went & made me spit coffee all over my computer (just kidding)Kurt
Yes, coffee help a lot, but I am in condition that coffee sometimes barely makes a dent in my performanceLOL - the older I get the more coffee it takes to get rid of the morning brain fog - LOL
Kurt
I have a neurological disease that makes me experience brain fog from time to time So I take it with scientific approach... Somebody corrects me or I will correct myself later on
when I re-read the post and realize what a nonsense I produced earlier Good that I can be of some assistance, cleaning your keyboard on the other hand is not in my job description
Kurt
You too.Yes, coffee help a lot, but I am in condition that coffee sometimes barely makes a dent in my performance
So I take it with scientific approach... Somebody corrects me or I will correct myself later on
I sometimes experience the opposite as well.
Did I really write this at that time, and I blame it on coffee, so I don't have to take the "blame" myself
I like that phrase in galenrog signature lineYou too.
I sometimes experience the opposite as well.
Did I really write this at that time, and I blame it on coffee, so I don't have to take the "blame" myself
Everything OK, maybe sometimes slow
