Why is fire sometimes blue and sometimes yellow colour?
404427
The different chemicals in the fuel change the color of the flame. For example, if you burn copper it turns blue/green. if you burn Lithium it turns red. Etc.
124988
The moon appears yellow when it is low in the sky (or even orange or red) for the same reason that the sun appears yellow when it is low in the sky (or even orange or red). \n\nNitrogen and oxygen molecules in the air are the right size to scatter away blue light from the mostly white light emitted from the sun (and reflected from the moon). This is called Rayleigh-Tyndall scattering, and there are many answers here dealing with that question. \n\nThis is the reason that the sky looks blue during the day, but during the night, with only the moon for lumination, there is not enough light to brighten the sky sufficiently for us to think it is blue. \n\nWhen the sun and the moon are low in the horizon, the light from these bodies travels through more atmosphere, so more blue light is scattered away, leaving orange or even red light:\n\n1. When the moon or sun is high in the sky:\n\n(whitish light from sun or moon)-(blue light scattered away)= (yellow light)\n\n2. When the moon or sun is low in the sky:\n\n(whitish light from sun or moon)-(more blue light scattered away because sun or moon is lower in sky)= (orange or red light)\n\nIt should be noted that the moon can not only appear whitish, yellow, red or orange, but because of refraction effects, can appear to have a green rim or a red rim (see reference), related to the green flash.\n\nAlso, if there are smoke or dust particles in the air, then instead of Rayleigh scattering, one encounters the phenomenon called nonselective scattering, where the red is scattered away, and the sun or moon appears blue. \n\nRayleigh scattering (blue gets scattered) occurs when the size of the scattering particle is smaller than the wavelength of the light. \n\nNonselective scattering (red gets scattered) occurs when the size of the scattering particle is about the same as the wavelength of the light. \n\nMie scattering (all colors scattered; causes the white of clouds and smoke) occurs when the size of the scattering particle is much larger than the wavelength of light.
396644
Like this?\nhttp://www.webelements.com/webelements/elements/media/pics/rainbow.jpg\n\nTo quote the web site,\n"The picture above shows the result of adding different metal salts to a burning reaction mixture of potassium chlorate and sucrose. The red colour originates from strontium sulphate. The orange/yellow colour originates from sodium chloride. The green colour originates from barium chlorate. The blue colour originates from copper (I) chloride. The lilac colour that should be evident from the potassium chlorate is washed out by the other colours, all of which are more intense."\n\nBasically, certain salts will color the flames various colors due to how the electrons are excited (more complicated than that, look into spectroscopy).
728020
any solution gives colour due to the fact that the outermost electrons absorb the energy and move to a highre orbit corrospondingly. when they come back to their orignal state, the enegry is emitted in the form of photons, which may have the wavelength crrspndngly to a colour.
750877
When salts of different metals are burned, they produce different colors. So, fireworks use metals to produce different colors.
233432
The color depends mainly on three factors:\n\n1: The material. Different materials burn with different color\n\n2: Temperature. A material subjected to different temperatures will glow with different colors. (The speed through the atmosphere will give different temperatures)\n\n3: Distance to object. Colors are spread because of the air in the atmosphere, just look at the Sun, red when the light travels far through the air and yellow/white when the distance is shorter.
478962
You can get a infrared thermometer. just point it at the flame and it will tell you the temperature. it will also show you the differences when you move to diff rent colors in the flame.. blue being hotter than the yellow.. i bought one on line for 39 dollars from eBay i think
873405
Flame color depends on several factors. Typically the most important being: blackbody radiation and spectral band emission with both spectral line emission and spectral line absorption playing smaller roles. In the most common type of flame, hydrocarbon flames, the most important factor which determines color is oxygen supply and the extent of fuel oxygen "pre-mixture", which determines the rate of combustion and thus the temperature and reaction paths, different color hues are thereby produced.\n\nIn a laboratory under normal gravity conditions and with a closed oxygen valve, a Bunsen burner burns with yellow flame (also called a safety flame) at around 1,000°C. This is due to incandescence of very fine soot particles which are produced in the flame. With increasing oxygen supply less blackbody-radiating soot is produced due to a more complete combustion and the reaction creates enough energy to excite and ionize gas molecules in the flame, leading to a blue appearance. The spectrum of a premixed (complete combustion) butane flame on the right shows that the blue color arises specifically due to emission of excited molecular radicals in the flame which emit the vast majority of their light well below ~565 nanometers in the blue and green regions of the visible spectrum.
1045718
Besides light and heat, they actually aren't similar at all. Fire is caused by an exothermic chemical reaction involving oxygen gas. Lightning is caused by electrostatic discharge between the ground and clouds, or between clouds.
696078
Yes, and yes. \n\nWhen organic compounds are burnt, their combustion reaction usually yeilds a range of colours from red to yellow. However, when hydrocarbons such as methane or ethane are burnt, their combustion reaction produces sufficient heat to produce a wider spectrum of colours such as blue. \n\nA combustion reaction occurs when sufficient heat is applied. If enough water is added to reduce the temperature to below that which produces the required activation energy (that is including the actual compound and its environment), then the flame will go out.
267281
Well.........\n\nThe blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air. \n\nHowever, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.
270266
Lightning can be any color. It is reflected off things that are near it, so it could be any color.
641178
"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." \n\nLet'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.
344738
Actually, this is a really hard one: color arises from light having different frequencies, and the different colors are reflected with varying efficiency from various substances: so a red color arises from a substance that reflects well low frequencies (red) and absorbs higher ones (blue and yellow).\n\nNow what determines in which way a given substance reflects light at different frequencies? That varies a lot: for starters, some atoms *are* in fact colored, that is, they reflect one frequency more  than another: chlorine gas is an example. This is also frequently the case for molecules (dyes). On the other hand, it is also often caused by some effect that cannot be traced back to the individual parts that make up the whole: think of a sand heap: clearly, none of the grains is a heap, nor is there any specific grain which gives the heap its peculiar properties. What makes a sand heap is just the large number of grains, all acting mutually one upon the other. A crowd, similarly, often does things you cannot really explain in terms of the individuals that make it up. Similarly, for example, a large number of copper atoms find a weird way of reflecting certain frequencies much more than others: it is a property of the whole substance that cannot be reduced to the individual copper atoms. Color, by the way, is not at all the only such property.
465006
Fire is not matter. The combustible material is a 'solid' like  wood, but can be a 'liquid' like gasoline. The wood combusts, releasing 'gases' such as Carbon Monoxide and solids such as ash particulates. The "fire" is the energy released in the form of heat and light. That's my simple explanation.
1077094
The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air...\n\nHowever, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue. \n\nThe atmosphere is the mixture of gas molecules and other materials surrounding the earth. It is made mostly of the gases nitrogen and oxygen. Argon gas and water (in the form of vapor, droplets and ice crystals) are the next most common things. There are also small amounts of other gases, plus many small solid particles, like dust, soot and ashes, pollen, and salt from the oceans.
329578
Fire isn't an element. It's a chemical reaction, or more precisely, a combustion reaction. A combustion reaction occurs when there is sufficient heat, fuel, and oxygen. The reaction is this:\n\nthing you're burning + O2 --> CO2 + H2O + other elements