Carbon dioxide laboratory preparation

In the laboratory, carbon dioxide is prepared most conveniently by treating a carbonate with a strong acid... 

In the laboratory carbon-dioxide is prepared by the action of marble or chalk (CaC03) with dilute HC1 or H2S04. 

Laboratory preparation. Carbon dioxide is prepared by treating calcium carbonate (e.g., Hmestone) with dilute hydrochloric acid ... 

Lead(II) carbonate occurs naturally as cerussite. It is prepared in the laboratory by passing carbon dioxide through, or adding sodium hydrogencarbonate to. a cold dilute solution of leadfll) nitrate or lead(II) ethanoate ... 

Carbon dioxide is present in air and is a eonstituent of natural gas eseaping from mineral springs and fissures in the earth s surfaee. It is also the ultimate produet of eombustion of earbon and its eompounds. Laboratory seale preparation usually entails reaetion between dilute hydroehlorie aeid and marble (ealeium earbonate) ... 

It is necessary to draw attention to the variable pH of water which may be encountered in quantitative analysis. Water in equilibrium with the normal atmosphere which contains 0.03 per cent by volume of carbon dioxide has a pH of about 5.7 very carefully prepared conductivity water has a pH close to 7 water saturated with carbon dioxide under a pressure of one atmosphere has a pH of about 3.7 at 25 °C. The analyst may therefore be dealing, according to the conditions that prevail in the laboratory, with water having a pH between the two extremes pH 3.7 and pH 7. Hence for indicators which show their alkaline colours at pH values above 4.5, the effect of carbon dioxide introduced during a titration, either from the atmosphere or from the titrating solutions, must be seriously considered. This subject is discussed again later (Section 10.12). 

An established school preparation of 2-propanone (acetone) involves the small-scale (and rather exothermic) oxidation of the alcohol with dichromate(VI). It was observed in several laboratories that when the acidified dichromate solution was added to the alcohol in small portions (1-2 cc) rather than dropwise as specified, small sparks or incandescent particles were produced which sometimes survived long enough to escape from the neck of the flask. This also happened if the alcohol and/or the oxidant solution were diluted with extra water, with old or new samples of alcohol, and if air were displaced from the flask by carbon dioxide. It is therefore important not to exceed the specified dropwise rate of addition of oxidant solution. It is very unusual for glowing particles to be produced from a homogeneous liquid reaction system. 

Interaction is exothermic, and if air is present, incandescence may occur with freshly prepared granular material. Admixture with oxygen causes a violent explosion [1], Soda-lime, used to absorb hydrogen sulfide, will subsequently react with atmospheric oxygen and especially carbon dioxide (from the solid coolant) with a sufficient exotherm in contact with moist paper wipes (in a laboratory waste bin) to cause ignition [2], Spent material should be saturated with water before separate disposal. Mixture analogous to soda-lime, such as barium hydroxide with potassium or sodium hydroxides, also behave similarly [1],... 

Ru electrodes were prepared as previously described by plating Ru metal onto spectroscopic carbon rods, except for the electrode used for Auger analysis (before and after carbon dioxide reduction) which was plated on Ti (2.). Cu electrodes were prepared from Cu foil as previously described (Kim, J. J. Summers, D. P. Frese, K. W., Jr. J. Electroanal- Chem. in press.). Each entry in the tables and figures was obtained on different days with the electrode kept in ordinary laboratory air overnight between runs. 

An extremely mild method for the synthesis of nitrate esters from easily oxidized or acid-sensitive alcohols involves the decomposition of a nitratocarbonate (29). The nitratocar-bonate is prepared in situ from metathesis between a chloroformate (reaction between phosgene and an alcohol) and silver nitrate in acetonitrile in the presence of pyridine at room temperature. Under these conditions the nitratocarbonate readily decomposes to yield the corresponding nitrate ester and carbon dioxide. Few examples of these reactions are available in the literature and they are limited to a laboratory scale. 

Although fire damp/ which is mainly methane, and choke damp (carbon dioxide) are frequent causes of mine accidents, Dr. William Brownrigg learned how to make good use of them. In 1741 he communicated to the Royal Society several papers on the gases of coal mines, but preferred to withhold them from publication until he could prepare a comprehensive treatise on the subject. His laboratory at Whitehaven was provided with several gas furnaces of his own design and a constant supply of fire damp from the nearby mines. Because of his skill in foretelling explosions by the rapid fall of the barometer, mine operators often consulted him. 

Rubidium acid salts are usually prepared from rubidium carbonate or hydroxide and the appropriate acid in aqueous solution, followed by precipitation of the crystals or evaporation to dryness. Rubidium sulfate is also prepared by the addition of a hot solution of barium hydroxide to a boiling solution of rubidium alum until all the aluminum is precipitated. The pH of the solution is 7.6 when the reaction is complete. Aluminum hydroxide and barium sulfate are removed by filtration, and rubidium sulfate is obtained by concentration and crystallization from the filtrate. Rubidium aluminum sulfate dodecahydrate [7488-54-2] (alum), RbA SO 12H20, is formed by sulfuric acid leaching of lepidolite ore. Rubidium alum is more soluble than cesium alum and less soluble than the other alkali alums. Fractional crystallization of Rb alum removes K, Na, and Li values, but concentrates the cesium value. Rubidium hydroxide, RbOH, is prepared by the reaction of rubidium sulfate and barium hydroxide in solution. The insoluble barium sulfate is removed by filtration. The solution of rubidium hydroxide can be evaporated partially in pure nickel or silver containers. Rubidium hydroxide is usually supplied as a 50% aqueous solution. Rubidium carbonate, Rb2C03, is readily formed by bubbling carbon dioxide through a solution of rubidium hydroxide, followed by evaporation to dryness in a fluorocarbon container. Other rubidium compounds can be formed in the laboratory by means of anion-exchange techniques. Table 4 lists some properties of common rubidium compounds. 

It will have been noted that in the formation of salicylic acid, only one half of the phenol is converted the rest is obtained unchanged. Schmitt (Dingier s Polyteehnisches Journal, 255, 259) succeeded in modifying the synthesis to obviate this defect, and his is the method always used industrially, although the other is more convenient in the laboratory. In Schmitt s synthesis sodium phenyl carbonate is prepared by heating up to 120°—140° dry sodium phenolate with carbon dioxide in autoclaves under pressure. Complete transformation of the intermediate sodium phenyl carbonate to mono-sodium salicylate then occurs on further heating. The carbon dioxide may be led in from a cylinder under pressure, or liquid or solid carbon dioxide may be mixed directly with the sodium phenolate in the autoclave. If preferred, the sodium phenyl carbonate can be prepared at ordinary pressures at 110° and then heated under pressure at 140°. 

It also reacts with carbonates to give normal salts, carbon dioxide and water, and with reactive metals to give a normal salt and hydrogen gas. The reaction between zinc and sulfuric acid is often used to prepare hydrogen gas in the laboratory (Figure 12.8). 

This reaction is used in the laboratory preparation of carbon dioxide (p. 214). It is also used as a test for a carbonate because the reaction produces carbon dioxide which causes effervescence and if bubbled through limewater turns it chalky white. 

Laboratory preparation of carbon dioxide and its properties (Figure 13.16, p. 214). 

Carbon monoxide is a poisonous gas. It is produced when carbon containing substances burn in insufficient air or oxygen. Its formula is CO. Compare this with the formula of carbon dioxide. As carbon monoxide is a highly poisonous gas, it is not prepared in the laboratory. 

Computer Chips. The manufacture of computer chips requires excessive amounts of chemicals, water, and energy. Estimates indicate that the weight of chemicals and fossil fuels required to make a computer chip is 630 times the weight of the chip, as compared to the 2 1 ratio for the manufacture of an automobile. Scientists at the Los Alamos National Laboratory have developed a process that uses supercritical carbon dioxide in one of the steps in chip preparation, and it significantly reduces the quantities of chemicals, energy, and water needed to produce chips. 

The one-pot procedure shown in Scheme 7.4 was found to be extremely robust on laboratory scale, but an unexpected problem arose upon scaleup in the pilot plant. Whereas the amidation reaction routinely reached completion within 12 h in laboratory experiments, it was found that 50 hours were required for the reaction to go to completion when carried out on multikilogram scale.24 An initial hypothesis for this unexpected drop in the reaction rate was that carbon dioxide, which is liberated in the CDI-mediated coupling, may play an important role in the reaction. It was postulated that CO2 may be removed more slowly from the large-scale reaction and would be available to react with diamine 18, thereby reducing the rate of the amide coupling. In an attempt to test this hypothesis, imidazolide 23 was prepared and used as the starting material for two parallel amidation reactions. In the first experiment, the reaction mixture was sparged with C02... 

The manufacture of sodium chlorite starts from chlorine dioxide C102. It can easily be prepared in a laboratory by heating a mixture of powdered potassium chlorate and oxalic acid to 70 °C. The gas escaping will contain carbon dioxide and chlorine dioxide. 

Figure 1 shows the simplified flow diagram of the laboratory equipment. First the extractor is filled with the prepared raw material and pressurised. Once the system has attained the required temperature and pressure, the carbon dioxide is expanded into the separator through a micrometering valve, and the extract is precipitated in the separator. The carbon dioxide is evaporated and its volume is measured by a gas meter. 

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