How does the temp change affect absorbance in a chemical reaction?
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.
251198
id say reactions can occur at any temperature above 0k. so 0.00000000000000000000000000000001K, the reaction would happen but really really really really relaly slowly. but thatz in theory. i have no clue bout pracitcally. i think the lowest temp theyve got to so far is either 4K or 0.6K. so ya.
891159
use the equation\nE(enthalpy change) = m(mass) c(specific heat) DeltaT(change in temperature)\n\ntemperature change is initial temperature minus final\nsince temperature increased then the temp change is negative\n\n-2.00C
200483
A calorimeter works by preforming some reaction (Usualy combustion) in a sealed container which is contained in a larger vessel filled with some liquid of a known specific heat (usually water).  When the reaction is preformed, it can either give off heat or absorbe heat to the surroundings (the water).  By measuring the temperature change in the water, we can calculate the amount of energy absorbed/released by the substance during the chemical reaction.\n\nhttp://en.wikipedia.org/wiki/Calorimeter\nhttp://hyperphysics.phy-astr.gsu.edu/hbase/thermo/calor.html
551973
TO CAUSE THE CHANGE CHEMICAL REACTION
732805
Increasing the temperature (adding energy) increases the molecular vibration.
675016
This is a calorimetry problem! There is an equation for it:       \nq = mc(change in temperature)\n\nq = the heat required \nm= mass\nc= specific heat \n\nAlso, write out the reaction and products.
685907
Temperature speeds up reaction rate.  Until you had the high temperature (flame) the reaction (gas burning) couldn't happen.  The temperature is then more or less constant unti the gas runs out, and then the reaction stops but not due to temperature, just due to lack of reactant.
97497
There are temperature changes is most reactions becuase there is heat generated, known as the heat of reaction.
20445
These are physical changes.  The matter simple changes state, depending on tempature.  Also see evaporation.
434523
* The heat content of a chemical system is called the enthalpy (symbol: H)\n    * The enthalpy change (H) is the amount of heat released or absorbed when a chemical reaction occurs at constant pressure.\n    * H = H(products) - H(reactants)\n    * H is specified per mole of substance as in the balanced chemical equation for the reaction\n      The units are usually given as kJ mol-1 (kJ/mol) or sometimes as kcal mol-1 (kcal/mol)\n      1 calorie (1 cal) = 4.184 joules (4.184 J)\n    * Energy changes are measured under standard laboratory conditions\n      25oC (298K) & 101.3kPa (1 atmosphere) \n\nEnthalpy changes are measured in KJ per mole, but experiments on measuring enthalpy changes always measure a temperature change. The temperature change is then converted to enthalpy change using the following formula:\n\nDH    =    m x c x DT\n\nm = mass in grams\n\nc = specific heat capacity in Joules/Kelvin/gram\n\nDT = change in temperature in degree Kelvin\n\nThe experiment  is done by simple calorimeter experiments which involve carrying out the reaction in a heat resistant vessel and measuring the change in temperature. \n\nThis is also a common practical assessment, and you should be aware of the sources of error in your measurements such as heat loss to surroundings, incorrect readings, inaccurate thermometers etc.
763107
Reactions can be classified as either exothermic or endothermic.  Exothermic reactions release energy, and cause the surroundings to increase in temperature.  Endothermic reactions absorb energy, and cause the temperature of the surroundings to decrease.
656932
Temperature only has meaning when you have a large enough quantity of particles to apply statistical mechanics to them. So, you are referring to a mass of, I suppose, a pure radiosotope. \n\nBeyond that it really depends.  Can be looked at in a fairly simple way.  That clump of neutrons and protons emits one or more particles and possibly a photon. What happens to those particles and photons makes a big difference in the impact they have on the surrounding material. If they are absorbed in some manner, a lot of their momentum will become momentum in the matrix (atoms and bonds between them) of the material. That means the temperature increases.  \n\nTo say how much it increases you need to know how much material is present, how well it absorbs the radiation it generates internally, and its thermal coeffecient (how much energy per mass/degree which depends on a LOT of things and will vary from substance to substance.)\n\nI recommend you go to wikipedia, or some other reasonably reliable source and look up "radioactive decay"  "temperature" and "chain reactions."\n\nSomething like plutonium will become noticbly warm in sufficient mass and in the appropriate shape (a sphere is nice) because the decay products from one atom are absorbed by the nuclei of more than atom on average, and these absorbtions cause THOSE atoms to decay in a short timescale, if you have chosen the right kind of atom. The net effect is the number of decaying atoms in the mass at any one point in time is pretty large and the thing heats up. The limit to this (why you don't get a runaway reaction) is closer to the surface (or due to impurities inside) significant amounts of the decay products are not absorbed by atoms that subsequently decay as a result.\n\nThat is why a small mass of U-235 will not "go critical" (almost all of it decays in a small time) whereas a larger chunk will.  Shape is important too, because clearly a very thin one atom thick sheet of the stuff would loose most of its decay products without setting off other atoms. A sphere is the most efficient shape in this regard. Finally, impurities matter because then you have non-reactive atoms absorbing some of the products so you are not setting off more than one atom for each atom that decays. That is why you can make a bomb with weapons grade U-235, but not less pure stuff.  The less pure stuff will still warm up because enough extra atoms get set off (suppose on average, each decay sets off 0.999999999999999 more decays) If the decays did not also happen spontaneously there wouldn't be any.\n\nLook up "chain reaction" in wikipedia also.
473273
temperature will rise depending on starting temperature, albedo(reflectivity), density, and probably lots of other factors, so there is no set answer.
908077
A high temperature will only favour those reactions which are endothermic. To be spontaneous, endothermic reactions require there to be an increase in entropy. You can understand this from the Gibbs Free Energy equation deltaG = deltaH - TdeltaS.  deltaG will tend to become negative as T increases.\nHowever, all reactions proceed faster with an increase in temperature, since a greater proportion of molecules have the minimum energy required to react - the activation energy.\nA low temperature will favour exothermic reactions, and will slow down all reactions.\n\nI do think that the question you are trying to answer is not a particularly good one.
770186
Basically what Le Chatelier's Principle is trying to say is that if a system in equilibrium experiences a change, then it will try and counteract that change.\n\nIn this case, the excess heat is the change experienced. To counteract the excess heat, some of it must be absorbed. Thus, the endothermic reaction in which heat is absorbed will occur at a higher rate than the other reaction. \n\nThe endothermic reaction is the forward reaction. (Equilibrium shifts to the right.) Thus, more N2O4 will be converted to NO2 than the other way round, resulting in less brown-coloured N2O4 molecules in the system. Therefore, the intensity of the colour will decrease.\n\n:) hope you find this useful!
904312
Lower temperatures reduce rates of reactions. This includes ezyme reactions in the foods that cause them to further ripen and spoil and growth of bacteria that can cause spoilage and food poisoning. It also keeps insects off the food and dust.