Why do Alkenes make bromine water go colourless?
815271
Br2 reacts with the double bond of an alkene.    The double bond disappears and the carbon atoms of the former double bond are now bonded to a Br atom.  Since Br2 is broken apart, then it no longer has the color.
153409
What specifically are you talking about, because I've never observed such a phenomenon.  I spent a year and a half working with sulfur dioxide and debugging a device designed to create it, and I've seen how it bleaches, and I don't know of any reversion to an "unbleached" state as you mention.\n\nReduction is NOT the removal of oxygen, and sulfur dioxide doesn't reduce anything.  Sulfur dioxide is an oxidizer.  Oxidation is the process by which electrons are removed from a reducer.  Generally, the way that this destroys color is by breaking the conjugated bonds in organic molecules that absorb color.\n\nIn some cases, color can be the result of the oxidation state of a metalic atom.  In an ionic state, it might have color, while it might become colorless when it is reduced.  Oxygen in the atmosphere could certainly make a metal atom become colorful (it turns copper green, iron red, etc).  But I can't see how sulfur dioxide could function as a reducing agent.
878601
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.
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.
1080141
"what element(s) and what bond(s) make water a universal solvent?"
223672
Could the bromine react with the iron to form FeBr3?  If I remember right, the Febr3 should make it easier to react with toluene (hence the iron catalyst).  I'm not sure about the math, but it seems like toluene was the excess reagent so FeBr3 shouldnt be leftover...\n\nDo you know if either of the distillation products are a bromotoluene?  From what you said, dibromotoluene could have come out.  Also, the methyl group has activating properties, so there will likely be more than one substitution, possibly even 3
796439
When chlorine is added to water it dissolves and forms a yellow solution. If this solution is allowed to stand in the sun the chlorine reacts with the water to form hypochlorous (HOCl) and hydrochloric (HCl) acids.  Both of these acids are clear when in solution with water.  In order for a color change to take place a chemical reaction has to occur and the resultant compound has to be colored.  In this case, if you add KF to chlorine water, a reaction is would not take place unless there are impurities in the water, and even then it is doubtful that a product would be colored.
967104
alkenes r more reactive as they can undergo addition reactions too due to the presence of double bonds while alkanes can undergo only substitution reactions.alkynes r evn more reactive as they hv triple bonds.\nwat is a soptier flame????\n\nbromine test.alkene will decolourize the bromine while alkane will not.
476397
bubbling the O2/Cl2 mixture through aqueous NaOH will remove the Cl2.  it reacts to give bleach ... NaOCl ... (and salt and water).  assuming you didn't want the Cl2 ;-)
774868
Cl is an halogene, like F or Br.  They all have the properties to kill germs (Cl in pool water, F in toothpaste, Br in surgical antiseptics).
742195
Alkaloids are amine-containing natural products; amines are basic (i.e. alkaline, hence the name).\nWith the exception of aspirin, the others you have mentioned are in fact alkaloids which happen to be white crystals. \n\nOrganic compounds are colorless unless there is some structural element within the molecule that absorbs color. This has nothing to do with bleach. Bleach does not turn organic molecules white--it usually causes a chemical reaction to take place.
801483
b. Tertiary bromide. Br2 dissociates into Br. + Br. The first Br. abstracts a proton preferentially from CH3CH2-C-H to give the most stable free radical (most stable because most hindrered and so least likely to revert to hydrocarbon again). That free radical abstracts Br from a new Br2, giving a tertiary bromide and generating a new Br. to continue the chain reaction.
23133
There are a few organic compounds which contain no hydrogen, but halogenes and optionally oxygen. Some of these are used as solvents for spectoscropy, or rather have been, being ozone killers.
527310
As you know, benzene is rather unreactive. Its conjugate pi system is entirely impervious to conventional nucleophilic and electrophilic attack. For example, you can react HBr with it forever, and you won't get Bromobenzene.\n\nWhat you have to do is to find a way to "pump up" the electrophile that is being used to attack the ring. When you run a bromination, you do:\n\nPh + Br2 ---> (w/ FeBr3 catalyst) PhBr\n\nAn Iron bromide catalyst works as a Lewis Acid to create Br+ in situ. This Br+ is electrophilic enough to promote the benzene's pi electrons to attack, forming the sigma complex and leading to bromobenzene.\n\nNitration works the same way. NO3 is not a strong enough nucleophile to promote the reaction. The H2SO4 is a stronger acid than NO3 and it protonates it, yielding NO2+ (HSO4 + H20 as spectators). This NO2+, called nitronium, is enough to cause the nitration of the benzene ring.
857657
BrO2 is bromine superoxide, which would give Br an oxidation number of +1 and oxygen an oxidation number of -1/2 , which is the requirement for a superoxide. I say this because I have never known bromine to have a +2 or +4 oxidation state it its compounds, and in oxoacids, its oxidation numbers are odd (from +1 in the hypobromite to +7 in the perbromate). This is why I don't pick +2, which would make it bromine peroxide. I don't pick +3, because that would require that oxygen have an oxidation number of -1.5 , which is impossible. Hope this helps!
1157873
This is what I'm pretty sure what happens: your digestive acids break up the pigments of color and turn it into a brown...waste. Yeah. Especially for plants. The chlorophyl just sorta...you know...disolves. As for why it turns into a brownish color, my only guess is that the digestive acides leave a sort of singe on it...oooor..................it could be that all the colors of the food blend together to form a brownish color (have you ever tried mixing all the colors of the rainbow together using food dye in water? Not pretty) But what do I know? Just ask a gastrologist...or whatever they're called....I guess I forgot...
759511
If bromine (Br2) is converted to bromide ions (Br^-), then it has gained electrons, ie it has been reduced (OILRIG is a handy mnemonic: oxidation is loss, reduction is gain of electrons).\n\nThe electrons gained by bromine in this reaction have come from the bisulfite, so bisulfite is the reducing agent and is itself oxidised:\n\nred: 2e^-  +  Br2  --->  2Br^-\nox:  H2O  +  HSO3^-  --->  HSO4^-  +  2H^+  + 2e^-\n\nredox: H20  +  HSO3^-  +  Br2  --->  2Br^-  +  HSO4^-  +  2H^+\n\nI hope that helps. If you need more assistance, please email me or re post.