Carbon dioxide, boiling point

If, however, the ammonia plant is obtaining nitrogen from an air separation plant, carbon monoxide and carbon dioxide (boiling points —205°C and sublimation temperature —78.5°C, respectively) may be condensed and removed by scrubbing with liquid nitrogen. 

The separation of nitrogen from natural gas reHes on the differences between the boiling points of nitrogen (77.4 K) and methane (91.7 K) and involves the cryogenic distillation of a feed stream that has been preconditioned to very low levels of carbon dioxide, water vapor, and other constituents that would form soHds at the low processing temperatures. 

The use of hops in the form of hop extract has spread rapidly the yield of the extract is better, yet insufficient. The production of a satisfactory hop extract quahty, ie, no taste difference to beer hopped by using other "natural" hop products, has appeared to be a science or art in itself Use of the right solvent and distillation is the key point, and many unsuccessful attempts have been made. The latest and most successful method, using the so-called Hquid carbon dioxide extraction, meets the high quaUty demands almost perfecdy. Preisomerization of the resins makes it uimecessary to boil them with the wort they can be added directly to the finished beer to avoid poor yield (through boiling) and the loss of resins (during fermentation). 

Formaldehyde is a gas with a boiling point of -21 °C. It is usually supplied as a stabilised aqueous solution ( 40% formaldehyde) known as formalin. When formalin is used as the source of the aldehyde, impurities present generally include water, methanol, formic acid, methylal, methyl formate and carbon dioxide. The first three of these impurities interfere with polymerisation reactions and need to be removed as much as possible. In commercial polymerisation the low polymers trioxane and paraformaldehyde are convenient sources of formaldehyde since they can be obtained in a greater state of purity. 

For work of the highest precision a comparison solution or colour standard may be prepared for detecting the equivalence point. For 0.05 M solutions, this is made by adding 5 drops of methyl red to a solution containing 1.0 g of sodium chloride and 2.2 g of boric acid in 500 mL of water the solution must be boiled to remove any carbon dioxide which may be present in the water. It is assumed that 20 mL of wash water are used in the titration. 

Notes. (1) Somewhat sharper end points may be obtained if the sample of water is first acidified with dilute hydrochloric acid, boiled for about a minute to drive off carbon dioxide, cooled, neutralised with sodium hydroxide solution, buffer and indicator solution added, and then titrated with EDTA as above. 

What does the phase diagram above show to be the normal boiling point of carbon dioxide ... 

Supercritical extraction is an important methodology for extracting organics from soil. As the name implies, the solvent is kept in its liquid state but above its boiling point by keeping it under pressure. Figure 12.8 shows a simplified supercritical carbon dioxide extraction setup. It is possible and common to have pumps, in addition to the one shown, to add chemical modifiers to the solvent, to increase extraction efficiency, or to extract a specific organic component [6,9-12],... 

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