Pre-lab: Identifying Carbohydrates

Analysis: Lab 1 Identifying Carbohydrates There were many ranges of color changes in the Benedicts test and Iodine stain. For the Benedicts test, this oxidation/reduction response changes the arrangement of the reducing sugar creating a colored precipitate. The change in color is correlated to the first concentration of the reducing sugar. For the iodine test, the three dimensional structure of various polysaccharides permits them to react with the iodine stain to produce a certain color. As far as the molecular level, there is an OIL – RIG method. Oxidation occurs when a substance gains oxygen or loses electrons or hydrogen (OIL – oxidation is loss) and reduction occurs when a substance loses oxygen or gains electrons or hydrogen (RIG – reduction is gain). Also, the distilled water (test tube one) served as a control for the experiment. Since polysaccharides are complex, the 3- dimensional sugars are often known as “complex carbs”. These molecules are composed of many elements of glucose linked together by the dehydration synthesis.
There were methods of determining whether a substance contained reducing sugars or polysaccharides. For the Benedicts test, the color changes of bluish green/greenish blue (trace amount +; honey solution, cornstarch solution, sweet ‘N’ low, sweet potato and egg yolk), green (++), yellow (+++) and orange red/rust (large amount +++: glucose/dextrose and equal) appeared, the concentration of reducing sugar indicated a positive test. Although, when the appearance did not change and remained the color of the Benedicts’ reagent of blue, indicated no reducing sugars, or a negative (-) test (water, table sugar solution, gelatin, egg white solution, and unknown (A3) solution). As for the Iodine stain, the color changes of bluish black (indicated plant starch; cornstarch solution and unknown A3), dark reddish brown (indicated glycogen), and violet brown to reddish brown (indicated cellulose; potato solution and sweet potato) presented