What are some advantages and disadvantages of the phenol coefficient test as a measure of chemical agents?
336797
The Phenol Coefficient test compares the potency of a disinfectant with that of phenol. A series of dilutions of phenol and the experimental disinfectant are inoculated with the test bacteria Salmonella typhi and Staphylococcus aureus, then placed in a 20 or 37 degree water bath. The highest dilution that kills the bacteria after 10 minutes exposure, \nbut not after 5 minutes are used to calculate the phenol coefficient.\n\nThe higher the phenol coefficient value, the more effective the disinfectant. A value greater than 1 means that the disinfectant is more effective than phenol.\n\nIts advantage is its ease of use.\n\nHowever, the EPA no longer recognizes a product's phenol coefficient as confirmation of its disinfecting capabilities since some products with high phenol coefficients were ineffective when used in the presence of certain organic matter and products with low phenol coefficients can be effective under \nactual use conditions.
96492
a test for unsaturation. In organic compounds, the unsaturation is due to presence of double (C=C) or triple (CΞC) carbon bond. \nThe test is performed as follows: To 1 ml of the aqueous solution of the organic compound in a test tube is added an aquieous solution of bromine (bromine water) dropwise. The mixture is shaken after each addition. The decolourisation of bromine water shows the presence of unsaturation in the organic compound.\nIn case the organic compound is insoluble in water, the test is performed by using the solution of compound in carbon tetrachloride and adding dropwise a solution of bromine in carbon tetrachloride.
910084
Depending on the pigment you are measuring, that is probably at the peak of the absorbance curve, and thus would be the most sensitive to changes in concentration, in accordance with Beer's Law.
110839
temperature changes de amount of energy in molecules, which has a direct efect on the amount of light transmited through a  solution and, therefore, afects absorbance.  Also, in chemical analysis, the formation of colored compunds is necesary and if the correct temperature is not set, the compound doesn't form correctly. (just some reaction mechanisms from organic chemistry)\nThe AOAC method for testing nitrate content in water is a good example. If you don't give the reaction the correct temperature, the colored compound will never form and the test is invalid.
954740
disadvantage is that mercury is very toxic. so if the thermometer breaks it is very dangerous. one of the reasons it is still used is because it can measure very high temperature. \nMercury will solidify (freeze) at -38.83 °C (-37.89 °F) and so may only be used at higher temperatures
518582
I don't really know, but usually when you're dealing with a coefficient/a ranking based on a known parameter, you have to use a standard item against which to measure. So things like specific gravity are based on an accepted level, and phenolic compounds would be measured against plants widely known to have a certain level.
252495
It's a relatively inexpensive way to measure the absorbance of aqueous solutions in the visible region of the spectrum.  Absorbances can be related to concentrations, so this is heavily used in quantitative chemical analyses.
180379
Like the refractive index of urine (specific gravity) it depends on the concentration of the dissolved solutes. Other than using it as a baseline in the assays mentioned above, I can think of little purpose in performing it. It is non-specific, and even a reading in the 'normal' range would not preclude an electrolyte imbalance.
772569
The Beer-Lambert Law forms the basis of Spectroscopy, an analytical tool for measuring concentrations.  Spectrophotometers are instruments used in laboratories to measure concentrations.  The most common is a UV/Vis spectrophotometer.  This instrument passes light(in this case UV or visible light) through a fixed length of solution and measures the radiation absorbed at a particular wavelentgh.  Thus the instrument gives an absobance reading of the solution.  Since the thickness or length of the solution is constant (the solution is placed in a glass cuvette, a little glass square that is of known length/thickness) from the Beer-Lambert law, the absorption is proportional to the concentration.  So, you prepare say three solutions of chlorophyll that are of three known concentrations (a high, middle and low standard) and measure their absorbance.  Now you measure the absorbance of your unknown sample.  Finally you use the mathematics of linear regression, to extrapolate the concentration of your unknown sample.\n\nThis is the most common and easiest way to measure concentrations in an analytical laboratory.
285706
I'm not sure what chemicals you are talking about.  However, Terminator Gold is what I use when I have to take a p*ss test.  You drink it a couple hours before you go in for the test.  You pee a couple times, then you are good to go.  If it's a hair follicle test there is a certain shampoo you can buy.  You can go to any local head shop and they will tell you what products to get.  My friends and I have all used terminator gold for years and it has worked for all of us.  It's also money back guaranteed.  \n\nOh, and ignore everyone else.  Smoke your brains out if you want.  Pot isn't bad for you, in fact, I think a lot of people would be surprised to find out how many positive effects smoking pot can have.  Good luck, hope you pass!
1059393
Yes, see below. They test it in environments to see if it adversely affects animals.\n\nI think there are better ways than to test it on/around critters...but I cannot be certain. I have sited all of my sources below. This does indicate that we subject critters to these chemicals before finding out if they are safe. Hence my answer, Yes!\n\nAs quoted;\nHazard to Humans and Domestic Animals are assessed by using a variety of acute, subchronic, and chronic toxicity tests.\n\n(Ie. Ignore the old hippie. Isn't it annoying when ppl respond and don't know what they are talking about?)
1150243
The easiest way to find out the answer to that question is to look up the MSDS.  It gives all the information you need about it's toxicity, reactivity, etc.  A lot of chemical supply companies have MSDS on their websites, and I think there might be a government website that has MSDS accessible online, but I'm not sure.
25944
It highly depends on what you're mixing.\n\nTypically, the good signs to look for are these:\nEvolution of Gas\nEvolution of Heat\nForming of Precipitate (two clear liquids become murky)\nChange of Color\n\nPretty much a change in any physical quality. If you want to figure out if a chemical reaction occurs without actually doing an expirement, look up "Reaction Spontenaity"
1167857
Advantages: \n1.  Links the physical and biological sciences.  (Biochemistry=chemistry of living systems, Quantum chemistry=physics of the atoms and their constituents)\n2.  Vital in pharmaceutical research\n3.  Vital in manufacturing (plastics, metals etc...)\n4.  Forensic research to help solve crimes (see CSI t.v. shows)\n5.  Vital in environmental research to help keep the environment safe (catalytic converters in cars help reduce harmful emissions)\n\nDisadvantages:\n1.  Chemical waste can be harmful to the environment and people's health (carbon monoxide, mercury).\n2.  It can be used in weapons (wmd's Saddam Hussein)\n\nThat's all I can think of right now.
235402
See comment above.\n\nYou do need to do several trials at various concentrations though. You can then determine it through a linear regression.\n\nI also suggest that you consult a book on Analytical chemistry, because Beer's law has limitations. For example, it loses linearity at higher concentrations.
151863
Either:\n\n(a) you're not getting a very clean separation, as the peaks should be vivid\n\nor\n\n(b) your detector is insuitable for the acids you're studying.\n\nAtleast, that's my analysis. Any A-Chem experts here?
1085913
Tollens' Test - Silver mirror.  \nUsing the appropriate chemicals formation of a silver mirror will indicate that your unknown is an aldehyde.  If not, it is a ketone.  This test is only useful if you have done tests to rule out other chemical possibilities.