Glass filter bottom

Filter off the barium sulphate precipitate and evaporate the solution in a porcelain bowl first on a flame up to one-fourth of its initial volume, and then in a water bath until dry, Rapidly cool the hot bowl with cold water to facilitate the separation of the precipitate. Extract the hydroxylamine chloride from the solution, for which end transfer the triturated substance into a flask with a reflux condenser, pour in 30 ml of ethanol, and heat it on an electric stove with an enclosed heating element up to boiling. Pour off the liquid into a beaker and treat the solid substance again with 15 ml of ethanol. Combine the ethanol extracts, filter them through a crucible with a glass filtering bottom, and then evaporate the filtrate in a water bath up to the beginning of crystallization. 

Preparation of Chromic Anhydride. Place 1 g of potassium dichromate into a porcelain bowl, dissolve it in 10 ml of water, and add ml of concentrated sulphuric acid while stirring with a glass rod. What substance precipitates Cool the solution and filter off the precipitate on a funnel with a glass filtering bottom. Write the equation of the reaction. 

Strongly acidify the filtered solution with hydrochloric acid and evaporate it to a syrupy consistence. Next add an equal volume of concentrated hydrochloric acid and let the solution stand for crystallization. Separate the crystals from the mother liquor using a funnel with a glass filtering bottom. What is the composition of the obtained compound What happens to the salt when heated What is the reaction of this salt to litmus Keep the crystals and the mother liquor for following experiments. 

In practice, the sample reservoir is quite small, and the task is made easier with a larger glass filter funnel firmly mounted to a laboratory stand. The height of the upward flow of water is controlled using a tube grip on the bottom discharge hose. 

For milk, transfer the entire sample extract into a separatory funnel (250-mL), add an equivalent volume of dichloromethane plus a half equivalent volume of sodium chloride solution (5%, w/v). Shake the separatory funnel for 2 min and allow the phases to separate. Partially fill a glass filter funnel with anhydrous sodium sulfate (approximately 10 g) and filter the lower dichloromethane layer through the sodium sulfate, collecting the filtrate in a round-bottom flask (250-mL). Wash the sodium sulfate with dichloromethane (5 mL) and collect the washings in the same round-bottom flask. Rotary evaporate the sample to dryness under reduced pressure with a water-bath temperature of 40 °C. Dissolve the residue in 4 mL of ethyl acetate-toluene (3 1, v/v) and transfer the solution to a suitable vial ready for GPC cleanup. 

Weigh 20 g (fresh weight) of chopped and homogenized plant samples into a 300-mL Erlenmeyer flask. Add 80 mL of acetone and shake the flask vigorously for 30 min with a shaker. In the case of brown rice and pea, add 20 mL of water to 10 g of sample and allow to stand for 2 h before adding 80 mL of acetone. Filter the extraction mixture by suction through a glass filter and re-extract the residue on the filter with 50 mL of acetone, then filter the mixture by suction. Concentrate the combined filtrate in the 300-mL of round-bottom flask to remove acetone at below 30 °C after addition of a 25% aqueous solution of potassium carbonate (0.2 mL). 

A 10-g amount of each minced and homogenized plant sample is weighed into a 300-mL volumetric flask, 100 mL of methanol-water (7 3, v/v) are added and the mixture is shaken vigorously for 30 min. The resulting mixture is filtered with a glass filter by suction. The residue is re-extracted with lOOmL of the same solvent and filtered. The combined aqueous methanol extracts are transferred into a 500-mL round-bottom flask and concentrated to 30 mL under reduced pressure below 45 °C. 

Rhodium(III) chloride trihydrate (2 g.) is dissolved in 70 ml. of ethanol (95%) in a 500-ml. round-bottomed flask fitted with gas inlet tube, reflux condenser, and gas exit bubbler. A solution of 12 g. of triphenylphosphine (freshly crystallized from ethanol to remove triphenylphosphine oxide) in 350 ml. of hot ethanol is added and the flask purged with nitrogen. The solution is refluxed for about 2 hours, and the crystalline product which forms is collected from the hot solution on a Buchner funnel or sintered-glass filter. The product is washed with small portions of 50 ml. of anhydrous ether yield 6.25 g. (88% based on Rh). This crystalline product is deep red in color. 

A 600-ml. coarse porosity sintered glass filter is recommended to shorten the filtration time. The filtration may also be hastened by periodically scraping the bottom of the funnel with a spatula. 

Dewar, liquid nitrogen, isopropanol Sintered-glass filter, diameter 8 cm 1L round-bottomed flask Rotary evaporator Column, diameter 7 cm Silica gel 60 (0.063-0.2) (Merck) (350 g)... 

Sintered-glass filter, diameter 6 cm 250 mL round-bottomed flask 500 mL round-bottomed flask Magnetic stirrer with hotplate Oil bath... 

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