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I am currently conducting an experiment into the glucose content of certain sports drinks. However, I have hit a roadblock. A majority of the drinks that I intend to test contain sucrose. I am thinking that by adding $\mathrm{1.0M~HCl}$, to say, $\mathrm{100~mL}$ of solution (sports drink), it will decompose the sucrose into its constituents. I'm planning to use Benedict's solution and a spectroscope in order to determine the amount of glucose present in solution (I'm going to add activated charcoal to the solution to remove the coloring from it before placing in the spectroscope). As a high school student I only have limited resources.

So my question is,

Assuming there is 10 grams of sucrose per $\mathrm{100~mL}$ of solution, what volume of $\mathrm{1.0M~ HCl}$ would be required to completely break apart sucrose into glucose and fructose?

Would I have to use stoichiometry to find the amount?

So far I know I have $\ce{C12H22O11 + HCl}$, What happens to the $\ce{Cl}$ from $\ce{HCl}$ when fructose and glucose is formed? Any comments or answers would be greatly appreciated.

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  • $\begingroup$ Um, you do know what the products are... You even told us what they are. $\endgroup$ – orthocresol Aug 3 '15 at 9:58
  • $\begingroup$ I understand that fructose and glucose are formed...But what happens to the Cl of the HCl? $\endgroup$ – Retty Aug 3 '15 at 10:52
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The hydrolysis of sucrose is acid-catalysed, so HCl will not be in the chemical equation (it will be listed above the arrow). In theory, this means that you could have little HCl, as it will never be used up and will keep reacting to decompose all of your sucrose. So it isn't so important how much you use, but you should still use enough that it won't take ages to decompose all the molecules. If you're interested you could look up mechanisms for acid catalysis, but you wouldn't be expected to know this at high school level.

To find the chemical equation for the decomposition, you can add up the number of elements of fructose + glucose and compare to sucrose. You will find that two hydrogens and one oxygen is needed, so it is simply a hydrolysis reaction (adding a water molecule).

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