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12 Cards in this Set
- Front
- Back
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Liquid in Distilling Flask |
Should onlybe 1/3 to 1/2 full, if too full will cause bumping Do notdistill all the liquid, will cause flask to explode |
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Distillation Set Up |
Clampflask, and fit the distilling head and thermometer (and its adapter) in complete vertical position Attach a clampedcondenser with the inlets facing upwards, using keck clips Attach avacuum adapter at other end and clamp and place a container underneath |
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Thermometer |
Recordsheat of the vapor, will take a while to increase since it needs to wait for vapors to reach it (position above the sidearm) Adjust heatso that collection rate is 1-2 drops per second |
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Collecting Fractions |
Forerun:fractions collected below 5°C of expected boiling point that should be discarded Record tempat which product fractions are collected |
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End of Distillation |
Leave someresidue or else flask will overheat and break or last drops will char Ethers,secondary alcohols and alkenes from peroxides by air oxidation and will explode if carried out to dryness |
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Fractional Distillation |
Many vaporizations and distillations happen before the distillate is collected Separate components of mixture based on their vapor pressure differences (less than 50 C apart) Use a vigreux column |
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Fractional Distillation Process |
Vapor cools to liquid as it goes up condenser then vaporizes again after it comes into contact with hotter vapor rising from below |
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Efficiency of Condenser |
Expressed as its number of theoretical plates One theoretical plate is equivalent to one simple distillation cycle Reported as HETP, lower = more efficient |
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Surface Area |
The larger,the more efficient the column will be (8 plates: 25° C apart) |
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Things to remember |
Doublecheck set up before turning on heat; remember to add 2-3 boiling stones |
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Types of Distillations |
Simple:remove low boiling solvent or last step in purification Fractional:Separate mixture of 2 or more liquid compounds whose boiling points differ byless than 60°-70° C Steam:Separate volatile compounds from complex mixtures Vacuum:when boiling point is over 200°C (reduce atmospheric pressure) |
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Changing Receiving Flasks |
Simple:change at 5° C beforeexpected boiling point Fractional: change after suddenchange in temp (indicating lower temp distillation is complete) |
