Advantages of flame atomization over electrothermal atomization in atomic absorption spectroscopy?
553247
Here is what I was able to gather:\n\nIn electrothermal atomization, the atom cloud is released into a relatively small volume of gas. In contrast, in flame atomization, the atom cloud is diluted by the high flow rate of gases and by expansion of gases during combustion;\n\n\nWith flame atomization, the liquid sample is aspirated into the flame by the venturi effect of the combustion gasses flowing through the burner. The flow of sample into the flame is typically in the range of several milliliters per minute. For this reason, flame AA requires milliliter-sized samples. With furnace atomization, a microliter-sized portion of sample is pipetted into a small, open-ended graphite cylinder, which is located in the light beam of the instrument, and the cylinder is then heated by applying a high electrical potential across the cylinder. The vapor cloud thus produced is contained within the cylinder. The result of this method of heating is not only the consumption of much less sample, but the generation of a much more concentrated sample vapor, which translates to much higher sensitivity. The drawbacks of this technology (electrothermal atomization) as currently practiced is that it is more expensive (due mainly to the cost of the graphite tubes), and takes significantly longer to perform an analysis than with flame atomization (minutes versus seconds), and the graphite tubes, which must be replaced relatively frequently, are expensive.\n\nI am not a Science expert and all I did was search for information - I do not own up to the answer. I hope it was helpful.
728971
(The) second experiment was to observe the reaction when a magnesium ribbon was ignited. The ribbon was put to the flame of a burner (delete ,) and was ignited. The reaction was very (intensive) (change to intense), and (burned with a) (delete was with) very bright white light. Usually when a substance is ignited in air, it reacts with H2 or O. In this case, because the Mg was the positive ion, it must have reacted with oxygen, (which is a ?)negative ion. In this experiment, because Mg was joined to O2 to make 2MgO of different composition, this was a combination reaction.\nThe third experiment 0.1 M CuSO4 and 6 M NH3 were used. CuSO3, a Sky blue liquid,  was place in a test tube, and then 1 drop of 6 M NH3 was added. Right after NH3 was added, the top of (the) liquid changed to navy color.  After the liquid was stirred the color of the liquid changed to a blue that was darker than the color of CuSO3. Ten more drops (of CuSO4?) were added to the contents, and the color of (the) contents changed to a violet color.
66666
There is probably not a strong relationship, but not zero either.  If the leaf is ignited the heat it gives off will convert combustibles to a gas that will also burn, leaving most minerals and metallic elements as ash.  The accumulation of ash could lessen leaf contact with oxygen but not with its gas.  Good combustion should depend more on how dry the leaf is and what its surface area vs volume is.  Minerals and metals likely would not aid combustion.  Early movie film was nearly pure cellulose (from plants) and was highly flamable.  It was nearly pure fuel, however, it hardly looked like a leaf to a flame.  Minerals and metals coating a leaf would inhibit combustion - by preventing ready contact with air.
617450
Some molecules absorb visible light, e.g. due to conjugation and pi to pi antibonding transitions, with the highest intensity at a particular wavelength.  One can prepare standard solutions, with accurately devised known concentrations, the measured intensities of these solutions are correlated with these standard solutions, covering a particular dynamic range.  Assuming Beer's Law, the plot will resemble a linear curve, and a least fit regression line and its equation can be obtained; also by correcting for the blank if this is has not bee accounted for by the spectrometer.  The unknown pure solution, or a matrix derived alternative method if the solution is not pure that there are significant impurities in the unknown solution, will also be measured at this wavelength and it's intensity, often the y value, will be plugged into the regression equation to estimate the concentration.
930664
I assume by quasion you mean question...\n\nK and Na can be determined qualitatively by a large variety of methods. One of them is inserting their salts in flame and examining the resulting flame color. The color diference is due to diferent energy for atomic excitation. This phenomenon belongs to chemistry but also to spectrometry and physics. \nI hope this answers your questions.
440509
There are many types exothermic or endothermic reactions.\n\n Exothermic reactions.\n1.Combustion reactions.(Except combustion of Nitrogen.)\n2.Combination reaction of anions & cations.(Ex-OH- + H+)\n3.Reaction of metals with non-metals.\n4.Some(1st) Electron affinity reactions(Expect elements of S2,P6,d10;Nitrogen)\n\n Endothermic reactions\n1.All the ionization reactions.\n2.Bond breaking reactions.\n3.Breaking into anions,cations.\n4.All the Sublimation,Vapuorization,Atomization reaction.\n5.(1st)Electron affinity reactions of S2,P6,d10 elements;Nitrogen\n6.All the 2nd,3rd electron affinity reactions \n\nSo,(a) is a exothermic  reaction\nAnd,(b) is also exothermic reaction
677394
Here are some of the more common applications of these techniques:\n\nGas Chromatography - Flame Ionization Detector, also called GC-FID.  This method is used to analyze mixtures of substances which have an appreciable vapor pressure and are capable of burning.  GC-FID is often used to periodically check a reaction mixture to see how far a particular reaction has gone.  It is also used to check for purity of the final product and to check for undesirable impurities.  \n\nHPLC can also be used in a similar way to GC-FID except that it is better at analysis of non-volatile compounds.  HPLC is often used to analyze the final purity of a product, or to analyze the concentration of a pharaceutical product in a physiological sample (blood, plasma, urine, etc).  \n\nUV-vis is good at measuring the concentration of a UV-absorbing compound in a matrix which contains no other UV-absorbers.  Sometimes you can take your final product and dissolve in non-uv absorbing solvent and measure the UV-vis absorbance to determine concentration or assay.\n\nThe above are just some of the more common uses.  There are many more uses for these techniques in the Pharma industry.
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In terms of clear crystals and clear solutions, they do not absorb light in the visible range.\n\nIn terms of flame test, they all contain sodium ions, which give off a yellowish light when heated.
278097
Pressure Swing Absorption: a special method for purifying gases (there is a very good presentation on UOP home page)
762389
I am not sure what you are asking.  However, if you want to know why it is important to use several different "knowns" or standards for comparison when doing a flame test, it is so you correctly identify the color observed in the flame and thereby correctly identify the ion(s) present.
787695
The nitrate ion is a good oxidizer, meaning it is reduced and the other species it reacts with is oxidized. The flame test is color dependent on the oxidation state (or number of electrons) present in the metal you are analyzing. So I would imagine that if you were analyzing something like the copper (I) cation in the flame, the color would change due to the fact that the nitrate ion is causing another oxidized copper species to be produced, such as copper (II), which has a blue color. Hope this helps and let me know if you have any other questions!
1120784
Well to start off any reaction that produces oxygen is potentially combustible, especially one that requires energy (endothermic) so be careful.\n\nTwo suggestions: \nFirst, electrolysis, this is where you break the covalent bond between oxygen and hydrogen with electricity (energy).  The by products are oxygen and hydrogen gas.\n\nMy second idea is simple rust.  Put iron (Fe) into water (H2O) and you will produce Iron-oxide or rust.  The Oxygen combines with the iron.\n\nGood luck.
490979
less elements, so less complicated maths.  \n\nYou get a less accurate result, which I don't consider an advantage.
26498
Atomic spectroscopy is the determination of elemental composition by its electromagnetic or mass spectrum. Atomic spectroscopy is closely related to other forms of spectroscopy. It can be divided by atomization source or by the type of spectroscopy used. In the latter case, the main division is between optical and mass spectrometry. Mass spectrometry generally gives significantly better analytical performance, but is also significantly more complex. This complexity translates into higher purchase costs, higher operational costs, more operator training, and a greater number of components that can potentially fail. Because optical spectroscopy is generally less expensive and has performance adequate for many tasks, it is far more common. Atomic absorption spectrometers are one of the most commonly sold and used analytical instruments.\n\nFind out more here: \nhttp://en.wikipedia.org/wiki/Atomic_spectroscopy
628384
In chemical qualitive analysis, this is known as a flame test.  Many metals (and some non-metals) have distinctive colors.\n\nThe heat of the flame excites one or more electrons of the metal atom causing it to go to a higher energy state.  When the electron returns to the "ground state" electromagnetic energy is released and this appears as light of a specific color.
612104
The explanations of fire in most standard reference works, not to put too fine a point on it, suck. The Encyclopaedia Britannica, for example, takes the following ineffectual stab: "rapid burning of combustible material with the evolution of heat and usually accompanied by flame." No wonder people have lost faith in science. Time to let a professional show how it's done. We'll start by reviewing the defects of the EB definition.\n\n(1) Rapid burning. OK, fire burns rapidly. Slow combustion, also known as oxidation, includes such nonfiery processes as rusting and digestion. However, to say that fire involves burning is to embark on a circular definition: What is fire? When something burns. What is burning? When something is on fire. We need to address the matter in more basic terms.\n\n(2) Combustible materials. Redundant. If a material is capable of rapid burning, by definition it's combustible. Also, "materials" is needlessly vague. One specific material, oxygen, is always involved.\n\n(3) Evolution of heat. I don't know what this is supposed to mean either.\n\n(4) Usually accompanied by flame. "Usually accompanied by" my arse. Flame is the quintessential pyrolytic phenomenon, not a mere by-product.\n\nNow for a proper definition, devised by myself: "Fire is the rapid combination of oxygen with fuel in the presence of heat, typically characterized by flame, a body of incandescent gas that contains and sustains the reaction and emits light and heat." Let's go through this bit by bit:\n\n(1) Rapid combination of oxygen with fuel in the presence of heat. Oxygen, fuel, and heat are the essential ingredients of fire. \n\n(2) Typically characterized by flame. The pup qualifier "typically" allows me to sidestep the issue of apparently nonflaming fires, like you get with burning charcoal. I suspect charcoal fires do create flame--you just can't see it due to the lack of impurities or incompletely burned fuel in the plume. (You can't see a fuel fire at an Indy or CART race either, because the cars run on clean-burning methanol.) But that's a matter we can leave for another day.\n\n(3) Body of incandescent gas. Flame defined. Most encyclopedia and dictionary definitions blow past this entirely, allowing persons such as yourself to imagine that fire is "pure energy" or similar nonsense. We say "body" because the gas has a characteristic structure and composition. We say "incandescent" because (a) it sounds scientific, (b) it means "luminous with intense heat," precisely what we are attempting to convey, and (c) if the Teeming Millions are going to learn one vocabulary word today, by God "incandescent" should be it.\n\n(4) Contains and sustains the reaction. Flame isn't just the result of fire; it is the fire. What's more, without the flame's heat the fire would go out.\n\n(5) Emits light and heat. Duh. However, we mustn't overlook the obvious.  \n\n>>>why do things that are put in it come out totally destroyed?\n\nOf course most things that go into fire aren’t totally destroyed. Most metals, glass, ceramic and so forth all emerge unscathed from fire. Even wood and paper aren’t totally destroyed, they leave an ash and charcoal residue as well as fine particles that we can see as soot and smoke.\n\nFire will ‘destroy’ anything organic that can be completely oxidised at the temperature that it burns at, but that is simply because the oxidation process converts the organic material to carbon dioxide,  and water. IOW the material isn’t destroyed it is just converted to gas and that gas blows away.\n\n>>>>>what fuel does it need from say, paper,\n\nThe paper IS the fuel the fire needs. The fire converts the paper into gases and ash. Or more accurately fire is the process of converting paper into gases and ash.
390022
the reaction is exothermic because the resultant solution or products is warmer than the reactants, assuming that it didn't warm up in the enviroment. In addition all neutralisation reactions are exothermic.\n\nThe solutions were mixed rapidly so that the concentration gradiant increases as quickly as possible preventing the reactants absorbing the heat from the reaction before the reaction is finished.  ie the initial rate of reaction being as high as possible.