Crucible Gooch

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. 

Fritted glass crucibles cannot withstand high temperatures and, therefore, should only be dried in an oven at temperatures below 200 °G. The glass fiber mats used in Gooch crucibles can be heated to a maximum temperature of approximately 500 °G. 

It is satisfactory to use the Super-Cel brand of kieselguhr supplied by Johns-Manville Company and asbestos of the type used in Gooch crucibles. Inclusion of these inert materials facilitates mixing and extraction of the product. 

Goochtiegel, m., Gooch scher Tiegel. Gooch crucible. 

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). 

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

Purified asbestos wool ( Gooch crucible asbestos for analysis ). Coarse and fine copper oxide. 

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. 

Porcelain Gooch crucible for ignition with a protective saucer. 

Take a properly prepared Gooch crucible, heat to constant weight and fit it into the suction flask. Decant most of the supernatant liquid first into the Gooch crucible by applying gentle suction to hasten filtration. Wash the precipitate on the Gooch crucible at least thrice with 15 ml portions of 0.01 N nitric acid. 

The filtration station can hold a Gooch crucible and/or beaker. 

An electronic balance is used to weigh a Gooch crucible or beaker. 

TTie filtration station cap has pin holes around the perimeter to allow residual sample drops to be rinsed out of Gooch crucibles with water. 

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. 

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... 

Dry HCl gas is passed for h through the ice-cold solution prepared in the previous step, and an emerald green solid is precipitated. This is separated by filtration through a sintered glass Gooch crucible (No. 4 pore size 5-15 pm), washed with concentrated HCl, and dried in a vacuum desiccator over solid NaOH. Yield 8.5-8.7g (87.8-89.9%). 

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