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10 Cards in this Set
- Front
- Back
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Why did you need to start the stopwatch immediately after adding the potassium manganate?
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As the reaction starts straight away so the stop watch needs to be started at the same time to accurately measure how long it took to be colourless
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Why did you need to wash the syringes after using them?
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As any traces of the liquid could affect the reliability of the experiment by changing the overall concentration of the solution
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How did you create a control variable for comparison between the solutions?
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Add glucose solution and sulphuric acid without the potassium manganate that colours the solution so that you can compare when it is the same clearness as the control variable
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Explain why lipids must be mixed in ethanol before they will form an emulsion in water
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Lipids are insoluble in water so they must be dissolved in ethanol first
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Explain how you could quantify the amount of glucose in a range of commercially available glucose drinks
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Use the benedict's test to see which drinks contain reducing sugars and determine the amount.
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Explain how you would proceed if the absorbance values you obtained for most of your unknowns were outside the range of your calibration curve
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Dilute the solutions so that they fit with the curve's range
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Explain the purpose of acid hydrolysis of a non reducing sugar before testing with Benedict's reagent
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To break the sugars down into monosaccharides by breaking the glycosidic bonds
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Explain why the emulsion of lipids, ethanol and water appears cloudy
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Lipids are not soluble in water so in order for them to be seen they must be first dissolved in ethanol
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Distinguish between structural and optical isomers in carbohydrates
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Structural isomers are compounds with the same chemical formula but arranged in different ways and optical isomers are the same carbohydrate but a mirrored image
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Explain briefly how compound sugars are formed and broken down
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Sugars are formed when two alpha glucose molecules form a glycosidic bond by a condensation reaction they are broken down by hydrolysis
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