Vacuum filtration, water trap

Cleaning Up Combine washings from the cotton in the trap and all aqueous layers, neutralize with sodium carbonate, remove zinc salts by vacuum filtration, and flush the filtrate down the drain with excess water. The zinc salts are placed in the nonhazardous solid waste container. Allow the ether to evaporate from the sodium sulfate in the hood and then place it in the nonhazardous solid waste container. Ethanol mother liquor goes in the organic solvents container. Any zinc isolated should be spread out on a watch glass to dry and air oxidize. It should then be wetted with water and placed in the nonhazardous solid waste container. 

The primary difference between the apparatus for simple and vacuum distillations is the attachment of the vacuum adapter to a vacuum source. Rather than being directly connected to the vacuum source, the adapter is normally linked to a heavy-walled sidearm flask. This flask has several functions. For example, if a water aspirator is being used to produce a vacuum, the flask serves as a trap to prevent water from backing up into the apparatus, which may occur if there is a sudden decrease in the water pressure in the aspirator. If it is equipped with a stopcock release valve, the flask also provides a means for connecting the apparatus and the manometer to the source of the vacuum and releasing the vacuum. Further discussion of traps is provided under the topic "Vacuum Filtration" in Section 2.17. 

Apparatus A dry 25-mL round-bottom flask, gas trap, ice-water bath, separatory funnel, apparatus for magnetic stirring, heating under reflux, vacuum filtration, and flameless heating. 

Turn on the tap to the water pump to the maximum water flow. If you do not do this, the water pump is not working at its maximum efficiency and the vacuum created in your filtration system may cause water to be sucked into a trap, or receiving flask, from the water pump. This is called suck-back . 

To traisfer the last of the solid/liquid from its beaker or conical flask into the funnel use a little of the filtrate in the receiving flask. Release the vacuum by opening the tap on the trap or pull dff the vacuum tubing, but do not turn off the tap on the water pump (there is a possibility of suck-back (see 9 above)). Dismantle the apparatus, pour a little of the ttitrate into the beaker of corii-cal flask, reassemble the apparatus and continue the filtration. Repeat until all the material has been filtered. Use the filtrate to wash down any of the solid sticking to the sides of the funnel onto the filter cake - it will not dry quickly on the sides of the funnel. 

All syntheses are carried out in an aqueous solution. Triflic acid, HSO3CF3 is distilled by the trap-to-trap method before use, and it is diluted with water (10 -10 M). Stoichiometric quantities of this diluted triflic acid is added to the lanthanide chloride or lanthanide oxide and heating at boiling for 30 min to 1 h. The unreacted lanthanide chloride or lanthanide oxide, if any, is removed by filtration, and the water is removed from the filtrate under reduced pressure. The resulting hydrate is then dried by heating under vacuum (1.33 Pa) at 180 °C to 200 °C for several days. 

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