Gooch filter

A porcelain Gooch filter crucible with a perforated base is supported on a series of indentations made in the middle of the tube. The oxygen inlet tube is located some 4-5 cm. below the indentations and is bent upwards so that the end of the tube is approximately 1 cm. below the crucible. The perforated base of the Gooch crucible is covered with a pad of glass wool to retain black particles of thallium oxide or metal, and then thallium shot is dried by pressing between wads of filter paper, and lOOg. of dried metal is placed in the crucible. 

Place a glass fiber filter paper circle (if required) into a clean, dry, Gooch filter crucible. Weigh the crucible on an analytical balance, and record the mass in TABLE 40.IB. Insert the Gooch crucible into a filter... 

Remove the aspirator hose, take apart the Gooch filter assembly, place the Gooch crucible on a watch glass labeled with your name, and dry the Gooch crucible and contents in the oven for about 1 hour at 110°C. Go on to part C while you are waiting for the Gooch crucible and contents to dry. 

Figure 2-12 Filtration with a Gooch filter crucible that has a porous glass (fritted) disk through which liquid can pass. Suction is provided by a vacuum line at the lab bench or by an aspirator that uses flowing water from a tap to create a vacuum. The trap prevents backup of filtrate into the vacuum system or backup of water from the aspirator into the suction flask.

Method 1. From ammonium chloroplatinate. Place 3 0 g. of ammonium chloroplatinate and 30 g. of A.R. sodium nitrate (1) in Pyrex beaker or porcelain casserole and heat gently at first until the rapid evolution of gas slackens, and then more strongly until a temperature of about 300° is reached. This operation occupies about 15 minutes, and there is no spattering. Maintain the fluid mass at 500-530° for 30 minutes, and allow the mixture to cool. Treat the sohd mass with 50 ml. of water. The brown precipitate of platinum oxide (PtOj.HjO) settles to the bottom. Wash it once or twice by decantation, filter througha hardened filter paper on a Gooch crucible, and wash on the filter until practically free from nitrates. Stop the washing process immediately the precipitate tends to become colloidal (2) traces of sodium nitrate do not affect the efficiency of the catalyst. Dry the oxide in a desiccator, and weigh out portions of the dried material as required. 

Purification of asbestos. Boil Gooch asbestos (tremolite, not chrysolite variety) with concentrated nitric acid, filter, wash free from acid, and dry at 100°. 

The liquid is filtered with suction through a Gooch crucible with a fixed porous plate (Note 1), and 100 cc. of water is added. The anthrone crystallizes at about io°. After being dried on a porous plate, it melts at about 153° (corr.). The yield is 80 g. (82.5 per cent of the theoretical amount). On rccrystal-lization from a 3 1 mixture (Note 2) of benzene and petroleum ether about 60 g. of anthrone melting at 154-155° (corr.) is obtained (62 per cent of the theoretical amount). 

A convenient apparatus for the addition of potassium tert-butoxide consists of a 250-ml. filter flask connected to the reaction vessel with Gooch tubing. The side arm of the filter flask serves as a nitrogen inlet. 

Weight of dried Gooch crucible after filtering the water 0.3837 g... 

For the filtration use a small filter tube with a fritted glass filter (cf. Fig. 41). Pour into the filter a suspension of finest asbestos (for Gooch crucibles) to form a layer 2-3 mm. thick after sucking dry at the pump. Before using the filter tube, pour in a little silver chloride precipitated in the cold. As soon as the filtrate is clear the tube is ready for use. 

A sample of 2.5 g (5.6 mmole) of 2,2 -bipyridinium pentachlorooxomolybdate-(V) is placed in a 100-mL, round-bottomed flask fitted with reflux condenser and a bent guard tube (filled with fused calcium chloride) to avoid entrance of moisture. About 20 mL of ethanol (98%) is added, and the materials are shaken. There is an immediate reddish-pink coloration. The mixture is heated at reflux for about 1 hour, until there is no more evolution of hydrogen chloride (tested with blue litmus paper). The mixture is then filtered through a dry sintered-glass Gooch crucible and washed twice with small quantities of ethanol. The product, a reddish-pink solid, is dried in a vacuum desiccator. Yield 1.5 g (71%). Anal. 

The resulting slurry is filtered thru a Gooch and the pulp sucked fairly dry. If analysis will show that the ethoxyl content is lower than de-... 

Gooch, Frank Austin (1852—1929). An American chemist, noted for analytical methods, especially as the inventor of "Gooch Crucible . It is a crucible with perforated bottom packed with glass wool or asbestos and placed in a funnel inserted in the stopper of vacuum flask. Can be used for filtering corrosive liquids Ref Hackh s Diet (1944), 386-L... 

Determination of water insoluble impurities. A portion of the sample of approx 10.0gf weighed to the nearest O.lg shall be dissolved in 400ml of boiling distd w. The soln shall be filtered thru a tared Gooch crucible equipped with a fine asbestos mat. The residue shall be washed... 

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