why do i need to boil a sample first in 50% NaOH before performing the lead acetate test...? please HELP!?
817375
lead acetate test is used for detection of iodide ion. \nso, let the sample salt be ferric iodide.This ferric iodide doesn't react easily with lead acetate . sample is boiled first in 50% NaOH solution as lead acetate reacts with NaOH to form NaI, which reacts easily  with lead acetate to form lead iodide(yellow ppt.)
70115
NaCl extracted with water more than once to ensure that all particles of the soluble substane have been removed.\n\nHope this helps,\nUltimeaciax
372647
No sample prep is really needed, just make sure the samples are pure.  Your injector needed will be a very small syringe, you will only need about 2 microlitres of sample.  The column will be small with a flow rate of about 1cm/sec.  Carrier gas would be helium flowing at a rate of about 100psi.  Detector would be a general detector that would detect organics, nothing special.  And your temp would need to be high enough to vaporize your highest boiling point hydrocarbon.  Probably somewhere around 80 to 100 degrees centigrade.  Good luck!
462489
put one of the acids in the titer, the other in the flask underneath.  Use a magnetic stirrer in the flask to ensure good mixing and ensure that you take required precautions (like goggles gloves lab coat ...possibly in a fume cupboard).\n\nThe two acids don't react with each other but is this 4:1 mix not acqua regia?
240386
Yes, I don't know the details but SDS will inhibit the bradford reagent.  You can use the BCA kit from Pierce for samples with detergents.  Also other things (lipids, salts) will give eronous readings.  Make sure to use a control of your sample buffer alone.
74804
I moved from the city to the country here in S.C. and had to put a well down. Look for DHEC. Should be one close. Its a State agency and they gave me a jar with instructions for  a sample. They tested it and the cost was free. Good luck>
735042
I'll address this as a formal type of trial, kind of give you the extremes first, and you'll need to tone it down to the level that you're looking to do.  \n\nFirst, and I'd say most importantly, you need to do this to much more than one egg.  What your teachers will be looking for is a stistically signifigant amount.  If you do one, your answer is 100% one way or the other, which isn't too helpful.  \n\nSecond, I would do each egg in "regular" water first.  Since, when they were boiled, they were already exposed to that type of water, there isn't much chance of them being contaminated in any way.  I would then make a chart something like this\n\nEgg #   |  Floated in norm...  |  Floated in salt...  \n   \n     1                        no                       yes\n\netc.\n\nYou'll want to, in some way, be able to compare these, so that you can quantify your results.  For example  "85% of the eggs tested were more boyant in salt water than in normal water..."  \n\nWays to improve\nThe only big thing I can think of here, with out changing this to a general which liquid is most bouyant, is be consistant.  Check and make sure that the water levels are close, you don't want 6 inches of salt water and only 4 of normal.  Check the temperature of the water, if one is hotter it will help its bouyancy.  Make sure to use the same mixture of salt to water each time, if you use more than one container.  And consider using bottled water, probably not necessary at all, but tap water has a lot of other stuff in it.  \n\nMost importantly, write down everything you do.  Say you checked the water temp.  Tell them that the ratio of salt to water was the same every time (and what it was).  The more details you give them, the more through you show yourself to be.  Have fun, maybe you can make egg salad after you're done!
585025
I don't know that you can, different solvents react differently to pressure, so I don't think it's a one eqaution fits all kind of process.  That's why they all have different graphs for phase vs temperature/pressure.  I'm sorry.\nSounds like you have a pretty high boiling point though, the things I've taken off that had to be real high temp were water, toluene, and pyridine.  Could it be one of them?  They smell pretty different, so you'd know which.  \nThat's an interesting question though, I've never stripped a solvent that I didn't know what it was.
621304
If you are dealing with a reaction involving ammonium carbonate in solution, and are then measuring the temperature rise, you need the heat capacity of water, not ammonium carbonate!\n\nPlease post the whole problem if that is not enough to get you started.
242714
Maybe the HCl concentration is too high?  Pepsin is active at pH 2.5.  Also how do you know the 'fish sample' is actually being broken down by pepsin?
526386
There is a phrase - PPPPPP - Prior Preperation Prevents Piss Poor Performance.  If you revise, you will at LEAST do as well as if you have not revised, but also have the possibility (probability) of doing a lot better.  Revision is recommended, but I wish you luck!
426561
If u added conc sulphuric acid instead of nitric acid carefully along the sides of the test tube, u would get a violet ring.This is actually a condensation product between alpha naphthol and 2-methyl furfural.
304287
This is called Base line correction.\nYour solvent may be having some absorption, or the impurities in it may be having some absorption..so to measure your compunds absorption exactly, you need to take the solvent (n whcih you are going to dissolve your compound later) and do this base line correction.\nIn a way you are telling instruments "NOT TO WORRY ABOUT THESE ABSORPTIONS"\n\nThats it\nYou got it?
449003
i would assume it depends on the plastic.  But NaOH pellets are stored in HPDE (high density polyethylene) plastic containers.  So my thinking is if concentrated NaOH is stored in plastic than the liquid should also be able.
903371
I have a serious feeling that you haven't given us all the info.\nIf you know the density of HCl you can get the first one.\nBut we don't have enough info to even begin to tell you the relevance of the NaOH.   More info, or concentrate on your own homework...
1082160
Those processes take special equipment. But generally, one takes a sample, boils it with the addition of either a solvent or an acid (depending what one is extracting) which releases the oils. From there, the solution may have to be dried, distilled, separated, or all three. HOWEVER, it absolutely requires that specialized equipment. ATTEMPTING an extraction without the right tools, protective gear, chemicals, forethought, planning, procedure, technique, and disposal could result in not only undesired products, but health concerns and issues ranging from burns, loss of conciousness, poisoning, carcenogenic effects, and even loss of life. It is highly not recommended to undertake the procedure if any  of these requisites are missing or lacking.
53470
Yeah, that's a good suggestion.  \nYou might also want to try stirring with a bulbous glass stirring rod or a rubber policeman very carefully.  Also, I think you'd be okay if you stir without making contact with the paper.  Perhaps the best suggestion, though, would be to pull through a little bit of your sample at a time; that way, your filter can handle pulling almost all of the liquid out of a small sample, then you add more in, etc., until it's all in and dry.