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Chemical And Physical Properties Of Carbohydrates

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Introduction Carbohydrates are defined by the following classifications: polyalcohols with aldehyde (known as aldose) or ketone (known as a ketose) groups, reducing molecules and water soluble. Additionally, carbohydrates can be grouped in several ways, as either monosaccharides, disaccharides or polysaccharides. Monosaccharides have one carbohydrate unit. Disaccharides have two carbohydrate units. Polysaccharides have many carbohydrate units. An example for each includes: glucose (monosaccharides), sucrose (disaccharides) and starch (polysaccharides). The initial purpose of the identification of unknown carbohydrates experiment was to identify unknown carbohydrates based on chemical and physical properties and understand that similarities and differences exist dealing with known carbohydrates.

Results
The following unknowns were tested: Unknown Carbohydrate 5 (Carb. 5) and Unknown Carbohydrate 7 (Carb. 7).
A. Fermentation Test:
Carb. 5 was positive for fermentation while Carb. 7 was negative for fermentation.

B. Benedict’s Test for Reducing Sugars:
Both Carb. 5 and Carb. 7 tested positive for the Benedict’s test. Based on the reaction timing, Carb. 5 reacted faster than Carb. 7 with the Benedict’s solution. Carb. 5 took a total of 3 minutes and 11 seconds to go through the color change that helps indicate whether it is a reducing sugar (blue to green to yellow to brick red), while Carb. 7 took 4 minutes and 33 seconds.
C. The Seliwanoff Test for Ketoses:
Both Carb.

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