What percent (by mass) of granulated sugar is fructose, and what percent of it is sucrose?
Background:
We are doing a colligative properties lab in my class where we are to add 20 grams, 40 grams, 60 grams, and 80 grams of sugar to 100 grams of water, and use the change in the water's boiling point to find the molecular weight of sugar.
I thought that granulated sugar was simply a homogeneous compound containing sucrose, whose dissacharide molecular structure contained a fructose molecule bonded to a glucose molecule, but my teacher told me that granulated sugar is in fact a mixture containing fructose and sucrose molecules held together by intermolecular forces. Which is it, and how should I tackle this issue in my lab writeup?
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I'm at a loss. I thought, and think, the same as you and from what I can read on the web that is still true. Also I read that solutions of sugar could sit for years without the glycosidic bond being broken. Nothing was mentioned about temperature; it could be that boiling the solution in the lab accelerates the hydrolysis but even if that were true you would have a mixture, in my opinion, of sucrose, glucose, and fructose. What to do? I don't know what to tell you. Sometimes I disagreed with my prof(s) but I did it very carefully.
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