what is the purpose of lead acetate test?,what is its positive result and reagents?
95933
Lead acetate test is used in qualitative analysis of Sulphides.\nWhen we add dil. Sulphuric Acid in the sulphides then H2S(Hydrogen Sulphide) Gas evolve.\nIf we bring a filter paper dipped in Lead acetate in the path of H2S gas then filter paper becomes Black due to formation of Lead Sulphide.
203972
I've done some research on this because I seem to remember my teacher talking in school about how they can make batteries with graphite (pencil lead) and vinegar that put out more energy and are more environmentally safe than regular batteries. I'm not sure how this happens but I know that you can take vinegar and pour some into powdered graphite, rub it into a block of wood, and when the vinegar dries the wood will be extra strong because the vinegar disolves the graphite long enough for it to bind to the wood. I can't find any research or projects to back this up but that is what I remember on the subject. Perhaps you could split a pencil and drop the lead in for a few days and see? Maybe use two and a nine volt battery and see what a current does to affect the chemical process...I wish I could help you more.
112035
As everyone knows by now, lead is poisonous. That is why we don't make lead pipes any more for plumbing (one of the potential reasons the Roman empire fell), or use tetraethyl lead to increase octane number in gasoline, or use lead-based paints. \n\nHowever, it is less well-known that lead is often radioactive. Natural lead is a mixture of four stable isotopes: 204Pb (1.48%), 206Pb (23.6%), 207Pb (22.6%), and 208Pb (52.3%). These lead isotopes are the result of the decay of uranium (Pb206), actinium (Pb207) and thorium (Pb208). There are also another 27 other radioactive isotopes of lead that are possible, but if they are present naturally, they are present only in tiny amounts. \n \n\n\nPb204 is only very slightly radioactive, with a half-life of 1.4e17 years (longer than the present age of the universe). Pb205 does not occur naturally, and has a half life of 1.53e7 years. Pb206, Pb207 and Pb208 are not at all radioactive. Pb210 is only present in trace amounts in the natural environment, and has a half life of 22.3 years. The decay products are alpha particles and beta particles, both of which are easily blocked (in contrast to gamma radiation).\n\nRecently, the State of Illinois determined that some products made with lead were contaminated with radioactive lead (see attached reference). However, on studying the problem, both the state of Illinois and the EPA decided that the hazards due to radiation were very limited.\n\nRemember, one increases substantially ones exposure to radiation by taking a plane flight, or by moving to Denver. The increase in radiation exposure has to be balanced against what is present in the natural environment. \n\nAlso, it is not clear how dangerous low levels of radiation are. There is a concept called radiation hormesis that has been around for a long time, but is now being reexamined carefully again. It is possible that small doses of radiation might be helpful in some cases (see reference).
1186885
I'm taking your question literally:  the lead (Pb) is on leads of a dual in-line package IC for through-hole applications, and the quantity of Pb is just the amount used for 'tinning' to promote solderability, and these are not surface mount packages.\n\nAlso, I'm assuming that:\nYou've confirmed the law applies to you (this is not networking equipment).\nYou've applied for and don't qualify under one of the exemptions.\nYou're shipping TO the EC countries.\nThese aren't cheap 'jelly-bean' devices you can just throw away.\nThey are plastic rather than ceramic packages.\n\nThere are three ways to remove the lead:\n1) Mechanically,\n2) Chemically (with acid),\n3) Solubility.\n\n1) Mechanical removal is usually not practical because of static electricity considerations, and, you can't get to all sides of the device.  It should be mentioned, however, the IC leads probably could withstand bending out flat (like gull-wings) so that you could get access to both sides, and use mechanical-abrasive methods to remove the lead (electronic grade baking soda abrasive blasting techniques for example, or residue-free CO2 ice blasting, mechanical sanding, etc.).   Depends on the static sensitivity of your device and especially how you 'ground' the device in a custom-built enclosed fixture to eliminate static damage.  Is labor-intensive, but doable to salvage an expensive device - suitable for low volumes - can be subcontracted to local shops for 'rework', but you'll have to spend time confirming that the ***very strict*** anti-static measures are implemented and adhered to on the shop floor.  I don't think any post-rework electronic testing is really going to catch static damaged parts (some will only be 'wounded' and will fail prematurely - short-term testing won't find this), so your only recourse is to avoid damage in the first place.  Bead-blast residues are relatively small and inexpensive to capture and dispose of.\n\n2)  Chemical methods would take advantage of the solubility of lead in certain liquids at room temperature (i.e, acids).  FUNDAMENTAL PROBLEM:  aqueous-based solvents WILL be absorbed into the plastic.  Further, acidic ions will remain trapped in the crevices by capillary action and migrate over time by diffusion directly into through plastic to the electronic device where corrosion could occur.  So the requirements for dissolution by acid are:  Acids that would eventually cause device failure are excluded (this eliminates HCL due to chloride migration to the wirebonds and subsequent corrosion),  acids that are difficult to rinse are excluded (sulfuric acid is notoriously difficult to rinse).  Further, it would only make sense to encapsulate the epoxy IC package in a protective covering to isolate the acid from the plastic packaging in the first place (thus tooling and extra labor expense is involved).  Acetic acid is a weak organic acid that *might* be usable, in that its diffusion through plastic is lower due to the larger molecule size compared to HCl.  You'd have to check acetic acid against solubility of lead vs. its compatibility with gold, silicon, aluminum, copper, epoxy used in IC manufacturing.  THEN you'd need to 'tin' the leads with some other metal (another expense).  After rinsing, the plastic packages would need to be 'baked' to drive off the moisture (and hopefully acetic acid residues if baking temp is above boiling point of acetic acid) - this must be done in a oven specially designed for removing humidity with a rechargable dessicant (an ordinary oven won't get the dew-point low enough; you need -80°F dew point or thereabouts), and you'd need to confirm by laboratory methods the acetic acid was gone.   Acetic acid is so slow acting that I don't think you'd want to wait around for it to work (time is money), but whatever the candidate acid, it would be one that you could remove the t
864893
If I remember correctly it is there to wash away any un-reacted reactants and also "neutralize" them. So if your proportions are not exact it will react away either of the reactants left since both would also be soluble in the ethyl acetate.
845828
Here you go...\n\nhttp://home.planet.nl/~skok/techniques/laboratory/pka_pkb.html
851017
B)   PbS  use the solubility rules. all leads are insoluble except with NO3, ClO4, and SO4....there is a list of solubility rules.
129216
I have clicked on the link and I read about a chemical substance(filter), that is called PBSA and is contained in some sunscreens. \nIt's impressing!\nWe put on our skin a product in order to protect it and we do exactly the opposite! Thanks for the information. I haven't heard about this, but BBC site is a trustworthy site, so this notice must be valid.\nI suppose that this special case is the result of a European Union program about chemicals, their detection and their elimination from our daily life.\n\nKaterina
262130
It is a strong oxidizer therefore used in sterilization or as a disinfectant. Its chemical formula is also known as peracetic acid C2H4O3.
457188
There are Lead Acid type, sealed batteries, Nicad batteries etc, describing all here is difclt, try web sites like wikepedia etc
450756
That's a perfectly reasonable experiment.  It addresses issues of solubility and phase equilibria.  As long as the project is done in a logical manner (i.e. following the scientific method), it should be a good project.
91801
What are they testing for?
445089
Yes ther is .. just visit this http://labs.google.com/
480971
acetates are ionic, and will more easily dissolve in water than an oil. thats your best bet.
1170877
There have been no reports of this product causing a false positive drug screen.\n\nDrug screening processes have grown more sophisticated. They don't test for remnants of chemical byproducts in the system anymore. They now test for traces of the drug itself. We get people in our police dept all the time who fail a drug test but say "I just took some Sudafed." The response is "Cool. We don't test for Sudafed. We test for methamphetamine. You failed."
784392
Here is what i found.  I'm not sure how right this is, but you can check it out.  Good Luck with your testing.
1008732
Ksp = [Pb+2]*[Cl-]^2/[PbCl2]\n\nby definition, [PbCl2] = 1\n\nAlso, based on the reaction:\n\nPbCl2 =====> Pb+2  +  2 Cl-\n\n[Cl-] = 2 [Pb+2]\n\nSubstitute this into the equation, and you get:\n\nKsp = [Pb+2] * [Cl-]^2 = [Pb+2]*(2[Pb+2])^2 = 4[Pb+2]^3\n\nNow, since you know that 0.99 grams of PbCl2 is dissolved in your liter of solution, you can calculate the molarity from:\n\n(0.99 g)/ (278.1 grams/mole) = 3.56x10^-3 moles = [Pb+2]\n\nKsp = 4*(3.56x10^-3)^3 = 1.8 x 10^-7\n\nThe text value for the Ksp of lead (II) chloride is 1.7 x 10^-5\n=================\nOkay, now for the second part of your question:\n\nIf you have 0.5M lead nitrate, which is soluble, you will have 0.5M Pb+2\n\nSo, let's plug 'n chug (we'll use the text value for Ksp to show the process):\n\nKsp =  1.7x10^-5 = [Pb+2]*[Cl-]^2\n\nbut, with the lead nitrate in solution, [Pb+2] = 0.5 moles/liter (the amount you'd get from the dissolution of lead chloride will be so small as to be negligible), so:\n\nKsp = 1.7x10^-5 = [0.5]*[Cl-]^2\n\n[Cl-]^2 = (1.7x10^-5)/(0.5) = 3.4x10^-5\n\nso [Cl-] = sqrt(3.4x10^-5) = 5.83 x 10^-3  and since [Cl-] = 2 [Pb+2], we halve that value to get:\n\nsolubility = 5.83x10^-3/2 = 2.92x10^-3 moles per liter\n\n(2.92x10^-3 moles/liter) * 278.1 grams/mole = 0.811 grams/liter\n\nIf you use the value of the Ksp calculated in the first half of the question, then the solubility of PbCl2 in your solution is 3x10^-4 moles/liter, or 0.083 grams/liter