HELP PLZ!! Can any one explains the reason for the behavior of sucrose with Tollen's and Benedict's reagents??
456017
Both Tollen's and Benedict's reagents are used for the detection of reducing sugars/aldehydes (such as glucose).  Sucrose is a disaccharide consisting of an aldehyde (glucose) and a ketone (fructose).  \n\nIn Benedict's reagent, sucrose is not broken down into its monosaccharide components and thus elicits no reaction/color change.\n\nIn Tollen's reagent, sucrose is broken down into glucose and fructose monomers, but this process occurs very slowly.  Thus you will eventually see the reduction of silver I to silver metal (as observed visually by "mirror" formation on the reaction container) as sucrose is broken down and glucose is liberated allowing it to react.
43485
Well, I'm not gonna try to explain this or anything, but check this website out:\n\nhttp://www.usm.maine.edu/~newton/Chy251_253/Lectures/Esterification/Esterification.html\n\nScroll down to "Scheme 2: Saponification of an Ester," and that explains the reaction process fairly well.  I don't know if this is what you're looking for, but I hope it helps!
25334
Apart from the reactions you will get when you dissolve glucose in water, which are mostly reversible when you crystallize the glucose, and the reactions when you dissolve salt in water (formation of a water molecule "coat" aka complex around the sodium ion), there will be no reaction between glucose and salt. \n\nSolubility of either compound will be reduced somewhat by the presence of the other compound. The addition of salt to an over-saturated glucose solution might start a crystallization process, but any over-saturated sugar solutions are hard to crystallize. Look at breakfast sirup or honey for an everyday occurrance.
462489
put one of the acids in the titer, the other in the flask underneath.  Use a magnetic stirrer in the flask to ensure good mixing and ensure that you take required precautions (like goggles gloves lab coat ...possibly in a fume cupboard).\n\nThe two acids don't react with each other but is this 4:1 mix not acqua regia?
604031
get the mass of sucrose that you're dealing with\n\nget the atomic mass of sucrose itself\n\nmass of sucrose / atomic mass of sucrose = moles
622135
Can you collect the vapors that came off the sugar, then mix the black residue with those vapors to reconstitute sugar.\n\nDissolve the sugar in water to make a solution, and then evaporate the water to reform sugar crystals -- no chemical reaction, just a change of state.\n\nChar the sugar (sucrose) with heat, and you are dehydrating it, according to the equation:\n\nC6H12O6 =====> 6 C(solid) + 6 H2O (vapor)\n\nCan you mix water vapor (or liquid water) with the carbon to reconstitute the sugar?  No! Therefore, you have a chemical reaction!
1180265
Try this link:\n\nhttp://www.sucrose.com/lbeet.html
900560
Most solutes (sugar in this case) have limited solubility (ability to dissolve) in most solvents (water in this case). This solubility varies with temperature - the hotter the solution, the higher the solubility. As mentioned in an earlier answer, this means more energy must be added to dissolve more solute. On the other hand, if energy is taken out of a solution, the solute will usually  come out of the solution, depending on the concentration.\n\nThis physical law that governs this is the 2nd law of thermodyamics.
296277
First of all, you're a nut.  Or at least a guy who likes to buy new microwaves.\n\nI'm not sure there is an actual reaction between sodium hydroxide and sugar.  For the sake of chemistry, we can treat all sugar as C6H12O6.  If anything the reaction will produce carbon dioxide and water, but this happens anyway when you burn any sugar so it might be hard to separate the two processes. \n\nWill check and get back to you  :)\n\nUpdate:  See the link below.  The only thing I can find is that NaOH will oxidize glucose, though this doesn't work as well for sucrose.  I don't think heating will have any effect other than to make the reaction go faster (and it already goes pretty fast, apparently.\n\nHave you thought about a career in chemistry?  You have the right kind of mind for it -- i.e., let's throw these chemicals together and see what happens!  By the way, I would NOT try this with NaOH and any kind of acid solution.  It might be dangerous under the wrong conditions.
1150312
Visit\nhttp://en.wikipedia.org/wiki/Benedict%27s_solution\n\nStill didn't get mail me.
512503
likely to be due to the osmotic gradient set up due to the high carboydrate concentration in the cytosol.\n\non the other hand, who cares?
958454
To visualize (C6H5)2CHBr, you have to identify the "side groups".  Obvious Br is one side group and so is one H.  Then you have two phenyl side groups so that leaves you that carbon to build on.  The molecule one carbon bound to two phenyl groups, one hydrogen and one bromine, each with a single bond.\n\nOK, let's build on that.  You are now going to react it with ethanol and you want to know what mechanism to expect.  Since Teach didn't show you the products, you're going to have to think about this one.  First, analyze what type of molecules you have.  The first molecule we spoke of, what type of carbon is the main carbon (primary, secondary, tertiary)?  What type of reaction (Sn1 or E1) does that type of carbon favor?  How about the ethanol?\n\nActually, the alpha carbon in ethanol, being a primary carbon, would favor Sn2 but that's not an option.  OH is an awful leaving group and alkanes don't like to carry a charge.  So we can rule the carbon out.\n\nThe problem must revolve around diphenylmethylbromide.  Having two phenyls would stabilize a positive charge fairly well and that is the first step for both E1 and Sn1 mechanisms.  So, which one is it?  The big giveaway is that En reactions are called elimination for a reason.  They lose a pair of substituents to form a double or triple bond, always a higher order bond.  Can there be any higher order bonds formed in this molecule?  How about Sn1, then?  That would result in (C6H5)2CH(OC2H5) + HBr.  Is this more likely than elimination?  Would this be endothermic or exothermic?\n\nThat's as much as I'm going to do.  The rest is for you, as you only really needed to know the structure of the first molecule.  But I hope this helps you understand what you are doing.\n\nGood luck.
789425
I think it has to do with the fact that there is a benzene ring on it. The pKa of benzene is around 7 or 8, I believe. So benzene could have a n affect on the level of its acidity. \n\nIt could possibly be harder for a base to pick up a proton off the alcohol on the phenol than on the alcohol on a regular carbon chain, or ring with no double bonds. \n\nbut I'm just guessing.
899653
A starch molecule is made up of 100's of glucose monomers. And each glucose monomer in a starch is linked with another glucose monomer by alpha -1,4 linkage due to which a starch molecule does not have a free aldehyde group which is opresent in a free glucose molecule. At its end it may have a free aldehyde group, but is too small in amount to show the reaction in comparision to a huge glucose monomer. As Benedict's Test is a test to determine presence or absence of a aldehydic group; a starch molecule can not show a positive glucose test. But if a starch molecuse is hydrolysed with help of an acid or amylase enzyme it will certainly show hte positive glucose test.
292071
What class was this in? What grade level? What text were you using?  I may be able to help you if I know the context in which the question was raised. I have a feeling that I am not getting all the information you had. Please tell me and maybe I can help. I am an old chemist and microbiologist.
760981
Hmmmm...interesting...I didn't think you could really do that experiment WITHOUT making a mess! :)  (And isn't mess-making, next to bang-making, one of the main attractions of chemistry?)  I guess you could point the bottle away from you, at an angle, pop the Mentos into it with your fingers, then pull your hand away really quickly.
777786
what affects buffers?\n\ndepends on which bufffers  -pH will with solubility, aas will temperature\n\nmaximum capacity depends on individual buffer - citric acid maxes at 3 base molecules, as does phosphates..\n\n\nnow to the question - what will you do for me?????   Good  thing I am a Christian - so i'll just take a thank you