Lab Report Essay example

879 Words Apr 22nd, 2013 4 Pages

All living things contain organic molecules such as lipids, carbohydrates, proteins and acids. In order to detect the presence of carbohydrates, proteins and lipids we have to do experiments.
The Iodine test is used to detect the presence of carbohydrates. This test is used to distinguish starch (polysaccharide) from carbohydrates. Reaction between starch and Iodine produce a dark grey, black color and it means that the test is positive. A yellow color means that test is negative. But other polysaccharides may give other colors including blue or red.
In order to detect the presence of glucose (monosaccharide) we have to use a Clinitest tablet. Clinitest tablets are usually used for urine sugar testing. If
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We mix them and let stand for a minute. Then we add a few grains of Sudan IV into the same tube. We cover out tube with parafilm then mix and let it stay.


Solution | Iodine | Clinitest | Biuret’s reagent | Sudan IV | Starch | Turned black | Turned blue | Light blue | --------------------- | Glucose | Turned yellow | Turned green | ---------------------- | --------------------- | Distilled water | Turned yellow | Turned blue | ---------------------- | Stayed clear | Albumin | ------------------- | ------------------ | Turned purple | -------------------- | Salad oil | -------------------- | ------------------- | ------------------- | Turned to red | 9
In Experiment 1 after we added Iodine to tube A1 (3 ml of starch) we could see a change of color. Due to reaction Iodine +Starch color changed to black. After we added 5 drops of Iodine into tube B1 (3ml glucose) color turned yellow. Then we added Iodine into tube C1 (distilled water) and color in this tube also turned yellow. So now we can say that the test is positive for starch. According to this experiment water and glucose got the same color what means that the test for the tubes B1 and C1 is negative because water doesn’t have anything inside. Iodine reacted with the starch and this reaction is positive for the polysaccharides (starch).
After we added

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