is a water-soluble organic compound that is easily oxidized and is therefore a good reducing agent. Iodine oxidizes vitamin C according to the following equation: CH2OH CH2OH H H C O O OH HO C 6H 8O 6 Vitamin C (Ascorbic acid) ϩ I2 → 2Hϩ ϩ 2IϪ ϩ O C O OH OH O O C 6H 6O 6 Oxidized form of vitamin C (Dehydroascorbic acid) Because aqueous iodine solutions are unstable and inconvenient to work with‚ you will titrate vitamin C samples in this lab
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chemical properties of these liquids. Acetone usually used as nail polish remover dissolves plastic. Vinegar used in cooking and as a condiment begins to fizz when mixed with baking soda. Hydrogen peroxide usually used as a disinfectant reacts to iodine solution and starts to bubble. Oil is used to keep food from sticking to non food surfaces and
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same concentration and amount of starch and amylase. After having each test tube placed in these environments for several minutes a droplets of each mixture was placed onto each slot which contained liquid solution of iodine. Each environment contained two different test tubes‚ one test tube was starch and the other was amylase. A droplet was placed in ten to thirty second intervals to see the different states of starch break up. When starch is present with iodine‚ the solution is a dark and transparent
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properties and structure. (http://www.ehow.com/list_5889717_four-macromolecules-occur-living-organisms.html) A few experiments were performed to test for the presence of the different types of macromolecules of various solutions. The iodine tested for starch and glycogen‚ Benedict’s test tested for reducing sugars for carbohydrates and biuret test was performed to test for proteins. It is necessary to understand how important controls are in a lab experiment. A control is where all of the experimental
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determined by analyzing the amount of iodine (I2) formed. Two chemical reactions are useful to determining the amount of iodine is produced. I2(aq) + 2S2O32-(aq) 2I-(aq)+S4O62-(aq) (3) I2(aq) + starch I2 *starch(blue complex) (4) Reaction (4) is an iodine-starch reaction‚ used solely to determine when the production of iodine is occurring by turning a clear colorless solution to a blue color. Without reaction (4) it would be very difficult to determine how much iodine is being produced‚ due to how
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nucleic acids. This lab exercise is designed to show you the qualitative tests commonly used to detect their presence. Objectives Test for the presence of monosaccharides by using the Benedict’s test Test for the presence of starch‚ a polysaccharide‚ by using the Lugol’s iodine test Test for the presence of lipids by using the Sudan test Test for the presence of proteins by using the Biuret reagent test Determine the identity of an unknown substance by detecting the presence of organic macromolecules
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forms a brick-red precipitate. | Sucrose | Reducing Sugar | As Benedict’s Test | Iodine Solution | Starch | A Blue-Black Colouration | Sudan III | Lipids | A Red-Stained Oil Layer separates on the surface of the water‚ which remains uncoloured | Biuret Solution | Proteins | Mauve or Purple Colour Slowly Develops | ‘ Table 2 . Biochemical Tests On Common Foodstuffs Sample | Proteins | Lipids | Starch | Sugars | Egg white | Turns Purple / +ve | Turns pale orange / -ve | Turn yellow/-ve
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turns yellow when cultured with fermentative microbes and only top few mm will turns yellow when cultured with oxidative microbes. B) Starch hydrolysis Not every microbe can produce amylase to hydrolyze starch. This session is to test the ability of microbes for the activity of starch hydrolysis. The presence of blue color upon the adding of iodine indicates that starch is not hydrolyzed. C) Gelatin Hydrolysis Gelatin is the convenient substrate to test for proteolytic enzymes in microorganisms. This
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is reached. If a substance contains molecules small enough to pass through a selectively permeable membrane then they will readily pass through it without the solution or substance‚ which is inside the membrane‚ getting out. \ Materials: String Starch Solution I2KI Solution Plastic cup Disposable transfer pipettes Strips of dialysis tubing soaked in water Timer Scale Method: First you will have your dialysis tubing soaked in water ready for the experiment. Once the dialysis tubing in
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teams research‚ the evidence sample contained starch. My team was also able to determine that the evidence sample dissolved in water ‚and felt like a powder. Performing different tests helped to determine the ingredients that the evidence consisted of. First‚ my team performed a water test‚ by mixing drops of water with the substances A through E and the evidence sample. The forensics then conducted a vinegar test and an iodine test‚ to test for Co² and starch. Finally‚ a heat test was performed‚ and
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