You conduct Lugol's iodine test to determine if starch is present in a solution. The solution exhibits a pale-yellow colour. What does this result mean? Question options: Starch is present in the solution. The solution has not yet been heated, which is required before determining the result. The solution is contaminated. Starch is not present in the solution.
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You conduct Lugol's iodine test to determine if starch is present in a solution. The solution exhibits a pale-yellow colour. What does this result mean?
Question options:
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Starch is present in the solution.
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The solution has not yet been heated, which is required before determining the result.
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The solution is contaminated.
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Starch is not present in the solution.
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- Will all carbohydrates gives a positive result with Molisch test? Explain your answer:A paste of starch was tested using Benedict’s test, the Iodine Test, and Fehling’s Test. Before hydrolysis, Benedict’s test and Fehling's test results were both negative while Iodine’s test is positive. After adding 0.5 mL of conc. HCl to the paste, another 5 drops of NaOH were added and was tested using Fehling’s, Benedict’s Test, and Iodine Tests. What would be the theoretical result of the three different tests? Explain the chemical reaction that happened and the principle/mechanism behind the reactions.The reults for the macroscopic part: 0.30M glycerin – solution was translucent (could see text behind the test tube) 0.15M NaCl – solution was opaque (could not see text behind the test tube) 0.30M NaCl – solution was opaque (could not see text behind the test tube) 0.15M glucose – solution was translucent (could see text behind the test tube) 0.30M glucose – solution was opaque (could not see text behind the test tube) 0.30M Urea – solution was translucent (could see text behind the test tube) Results for microscopic part: 0.30M glycerin – no cells present 0.15M NaCl – normal sized cells 0.30M NaCl – crenated (shrunken and star-shaped) cells 0.15M glucose – no cells present 0.30M glucose – normal sized cells 0.30M Urea – no cells present Determine the osmolarity (hypoosmotic, isosmotic, or hyperosmotic) and tonicity (hypotonic, isotonic, hypertonic) of the following solutions.In which solutions did the osmolarity NOT match the tonicity? For those solutions, why did the osmolarity…
- You purchase a premix flour containing iron (Fe), riboflavin, niacin, thiamin, and folate. For determination of Fe concentration in the flour sample, you conducted an atomic absorption spectrometer (AAS) experiment using known concentration of Fe (standard). About 10 g of flour sample is used and mixed in 100 mL of solution then measured using AAS. 1.2 0.8 0.6 0.4 0.2 8 10 12 -0.2 Fe concentration (mg/L) [a] If the absorbance value of the flour sample is at 0.35, calculate the Fe concentration presence in the flour sample (obtained equation from the standard curve is y = 0.1018x - 0.0514). [b] Commonly, the Fe contents are in the range of 1.6 mg to 2.3 mg in 100 g super flour to comply with FDA's standard of identity. Based on your calculation, justify if the Fe concentration in the flour sample comply with the FDA specification. Absorbance at 248.3 nmQualitative Analysis of Carbohydrates HELP Iodine reacts with starch to form a starch/iodine complex, which gives a characteristic blue colour to the reaction mixture. Glucose, lactose and sucrose do not give this reaction. Select the test: Iodine test A Iodine Solution Reset Glucose Lactose Sucrose StarchCOMPLETE THE TABLE BELOW: The six tests for the detection of functional groups in amino acids and proteins. TEST REAGENTS POSITIVE RESULT POSITIVE INDICATION
- The following figure shows the fatty acid profile of the lipid samples tested for bromine test. Rank the samples based on the number of drops. (1- the highest number of drops; 3- the lowest number of drops)In starch test describe and explain the change color in results:A. Yellow to BrownB. Blue to BlackBelow is a list of instructions for an experiment to test different foodstuffs for the presence of starch. Rewrite the instructions as the method for an experiment you have conducted. Equipment required: potassium iodide crystal, bleach solution, plastic sheet, moistened paper towel Suggestions for foodstuffs for testing: pasta, bread, cereal, potatoes, mushrooms, apple, cheese and cooked chicken. a Place a small piece of each of the foods to be tested on the plastic sheet. b Place a small potassium iodide crystal on top of the piece of food. c Add one drop of bleach solution (sodium hypochlorite solution) and allow it to run over both crystal and food. d if an intense blue-black colour is seen, the food contains starch. e Clean the plastic sheet with a moistened paper towel.
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