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  • Updated 6 months ago - 93 words
    The RasMol scripting language has two synonymous commands to control atom size, spacefill and cpk (for Corey, Pauling, and Koltun). As an extension to the RasMol scripting language, Jmol allows you to specify your size as a percentage of the vanderWaals radius. If you want to specify a fixed size then you can do so in Angstroms. Note that the last button specifies "1.0" instead of the integer "1". This is important because integer values specify RasMol units (1/250th Angstrom)
    http://chemwiki.ucdavis.edu/Biological_Chemistry/Metabolism/Caffeine
  • Updated 6 months ago - 388 words
    What is the order of the reaction for all of the reactants? (5) What are your observations on the linearities of your data as you change the concentration of reactants? (20) Does the linearity assumption vary with reactant concentration?
    http://chemwiki.ucdavis.edu/Wikitexts/UC_Davis/UCD_Chem_125%3A_Lab_Manual/Bromination_of_Acetone_Lab
  • Updated 6 months ago - 321 words
    By adding a removable fritted glass tube, and closing the solvent return tap, the setup below can be used to extract water continuously with a solvent less dense than water (such as diethyl ether). As the methylene chloride is evaporated it will condense by a water condensor (not shown, above the image) The liquid will follow through the aqueous solution and then through the glass path into the round bottom flask (c).
    http://chemwiki.ucdavis.edu/Reference/Lab_Techniques/Liquid-Liquid_Extraction
  • Updated 2 months ago - 506 words
    The low temperature of these baths is determined both by the appropriate use of solvent as well as a cryogenic agent such as liquid nitrogen, dry ice (CO 2 ) or ice. Dry ice/acetone: Slowly adding acetone to dry ice will minimize the amount of dry ice you need to handle. Alternatively, you must slowly add dry ice to the acetone or the large volumes of carbon dioxide produced will cause rapid bubbling.
    http://chemwiki.ucdavis.edu/Reference/Lab_Techniques/Cooling_baths
  • Updated 6 months ago - 1,449 words
    Basically, you need 1) a tube that goes from the airvent (?) near the stopcock to your Erlenmeyer full of solution to be rotovapped, 2) an internal tube from the stopcock that reaches down past the condenser tubing, through the rotating shaft and into your bump trap and 3) an appropriate bump trap that allows your solution to reach your attached rotating round bottom. (One of these works fine (http://www.safetyemporium.com/?CG-1319-04) -- basically, you can't have the "standard" bump trap.) Fir…
    http://chemwiki.ucdavis.edu/Reference/Lab_Techniques/Rotary_Evaporation
  • Updated 1 month ago - 1,970 words
    Having said that scientists have determined the best size I’m going to now say that there are no real rules to the picking of the column, since the amount of silica gel you use, the length of the column, your solvent system… all these things go into making a decision.
    http://chemwiki.ucdavis.edu/Reference/Lab_Techniques/Packing_Columns/Packing_Normal_Phase_Columns
  • Updated 6 months ago - 770 words
    If we draw an analogy to a waterfall, the voltage would represent the height of the waterfall: the higher it is, the more potential energy the water has by virtue of its distance from the bottom of the falls, and the more energy it will possess as it hits the bottom. Then current represents how much water was going over the edge of the falls each second . Resistance refers to any obstacles that slows down the flow of water over the edge of the falls (e.g.
    http://chemwiki.ucdavis.edu/Analytical_Chemistry/Electrochemistry/Voltage%2C_Amperage_and_Resistance_Basics
  • Updated 3 months ago - 439 words
    Sodium azide is used as a source of azide anion which is a strong nucleophile that readily displaces suitable leaving groups. For a detailed description of how to quench sodium azide see the Health and Safety provided by Northeastern University: http://www.ehs.neu.edu/hazardous_waste/fact_sheets/sodium_azide/. It can be quenched by nitrous acid With stirring add a 20% solution of sodium nitrite containing 1.5 g of sodium nitrite per gram of azide
    http://chemwiki.ucdavis.edu/Reference/Lab_Techniques/Reagent_Specific_Hazards/Sodium_Azide
  • Updated 6 months ago - 1,373 words
    When you blow air into a balloon, the balloon expands because the pressure of air molecules is greater on the inside of the balloon than the outside. The standard atmospheric pressure is "the pressure exerted by a mercury column of exactly 760 mm in height when the density of mercury= 13.5951 g/cm 3 (0 degrees C) and the acceleration due to gravity."
    http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Phases_of_Matter/Gases/Gas_Pressure
  • Updated 1 month ago - 707 words
    This type of pump can achieve high to ultra high vacuum, but can not discharge directly to the atmosphere and must use a secondary pump to maintain low pressure at the outlet. The difference between the levels of the mercury when these are vertical gives the pressure of the system (the instrument should have its own scale, which should be zeroed to the level of mercury in the open capillary).
    http://chemwiki.ucdavis.edu/Reference/Lab_Techniques/Vacuum_Equipment
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