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.
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)
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
Check with your enviromental safety officer for a complete list of rules and a long boring lecture on how to properly dispose of hazardous waste. However, most of the rules can be generalized under a few guidelines which should always be kept in mind when dealing with chemical waste. It is acceptable to decontaminate some biohazardous solutions with bleach or similar disinfectants and dispose of them down the drain, others must be autoclaved.
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).
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).
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.
Typically there is a "shutter" that can be used to reduce the amount of heat transfer from the heating jacket to the first Kugelrohr flask - this should be closed. If needed, most Kugelrohr setups will allow you to "insert" the second Kugelrohr flask into the heating jacket - by doing this and reducing the temperature slightly, it is possible to produce a more pure distillation.
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.
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…