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13 Cards in this Set
- Front
- Back
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what is filtrate?
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the liquid collected after a filtration
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Regarding experiment #1: in a CH2Cl2 and H2O mixture, which solvent will be the bottom layer
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methylene chloride bc it has a greater density then H2O
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regarding experiment #1: will all of the caffeine go into the dichloromethane layer?
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no, some will remain
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what is the purpose of washing the organic layer with a solution of saturated NaCl?
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to get rid of more H2O and impurities from CH2Cl2
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regarding experiment #1: caffeine is (soluble/insoluble) in water whereas the binder is (soluble/ insoluble).
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soluble, insoluble
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regarding experiment #1: what is the literature melting point of caffeine?
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234 ˚C
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regarding experiment #1: what is the literature boiling point of methylene chloride?
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39-40 degree celsius
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regarding experiment #1: in the procedure for this lab, the directions state to " cool the filtrate by adding ice chips until the solution is at room temperature". why is it necessary to cool the filtrate before adding the methylene chloride?
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CH2Cl2 (methylene chloride) has a boiling point of 40˚C so if the H20(filtrate) is greater then 40˚C it will boil away the methylene chloride
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regarding experiment #1: when using a rotary evaporator, the water bath is typically kept at a temperature below the normal boiling point of the solvent to be evaporated. why will the solvent evaporate at a temperature below the normal boiling point?
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bc a vacum is usually applied to the setup the boiling points of the solvents are going to be significantly lower than at ambient pressure. in addition the flask is being rotated, increasing surface area which increases the evaporation rate.
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regarding experiment #1: what did the IR read for caffeine as far as functional groups and peaks?
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3112= aromatic
2954=CH3 1696=amide |
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all glass must be disposed of by which of the following?
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in the "broken glass boxes" in each lab
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caffeine is soluble in water ( 2g/100 mL ) and also in methylene chloride (10g/100 mL). what is the distribution coefficient of caffeine in methylene chloride versus water?
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5
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during the isolation of caffeine experiment, the caffeine was extracted from an aqueous solution into methylene chloride. the next step in the procedure was to wash the methylene chloride extracts with saturated sodium chloride solution (aq). what was the purpose of the wash?
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the sodium chloride removed any suspended water from the methylene chloride.
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