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6 Cards in this Set
- Front
- Back
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Biodiesel synthesis reaction
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triglyceride+3alcohol --catalyst--> 3biodiesel+glycerol
-waste cooking oil has triglycerides (esters w/ a glycerol part and 3 fatty acids; R groups on fatty acids differ based on what oil is used) -alcohol (methanol or 1-propanol in this) and an acid (H2SO4) or base (NaOH) catalyst is used -the starting material and product are esters, so this rxn is a transesterification |
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Possible problem for base-catalyzed biodiesel reactions
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-water released from food being cooked can hydrolyze an oil's triglycerides and form free fatty acids, long-chain carboxylic acids, which the base can react with the form soap, which isn't flammable (saponification)
-free fatty acids don't usually cause problems for acid-catalyzed biodiesel rxns |
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what to do with the glycerol
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-remove the glycerol before the biodiesel can be used for combustion
-easy b/c they are immiscible (don't mix) and glycerol has a large density |
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In general, what are we doing in this lab?
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-test effects of various fuels on radish seed germination
-synthesize biodiesel using 3 different methods |
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Ecotoxicity assay steps
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-get assigned 1 of 4 fuels (biodiesel, 2-butanol, methanol, ethanol)
-get 6 petri dishes, put a piece of filter paper in each, put 30 radish seeds in each -make 20 mL of a 10% solution for your certain fuel, and put 10 mL of it into your 1st petri dish -Dilute to make 5%, 2.5%, 1.25%, and 0.625% solutions and transfer 10 mL of each into the other petri dishes -put 10 mL deionized water in the last petri dish -seal the petri dishes/store them |
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Synthesis part 1 steps
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-put 20 mL of waste cooking oil into a beaker and warm it up on a hot plate to between 40-50 degrees C while stirring w/ a magnetic stir bar
-turn off heat -add sodium hydroxide in methanol solution, or sodium hydroxide in propanol solution, or sulfuric acid in propanol solution to warm oil -stir rxn for 45 min -let samples cool, put in conical tubes/store in drawer |
