Air-free water

Before use, the marble chips are washed repeatedly with hot water, and then de-aerated by first etching them with concentrated hydrochloric acid and then boiling them with air-free water under reduced pressure. The chips are then rapidly transferred to the generator small chips should be used and the bulb... 

Apart from the black Re203.2H20 (which is readily oxidized to the dioxide and is prepared by boiling ReCl3 in air-free water) oxides of oxidation states below -t-4 are known only for manganese. Mn304 is formed when any... 

Determinations have been made of the solubility of lead linoleate prepared in the absence of oxygen and extracted with air-free water. Under these conditions, lead linoleate had a solubility of 0-002% at 25°C and the extract was corrosive when exposed to the air. When, however, the extraction was carried out in the presence of air, the resulting extract contained 0 07% solid material and was non-corrosive. It was concluded that in the presence of water and oxygen lead linoleate yielded soluble inhibitive degradation products. 

Add 0.5g hydroxylammonium chloride (to prevent oxidation), and 3mL triethanolamine (to prevent precipitation in alkaline solution) use boiled-out (air-free) water. 

Procedure. The solution should contain antimony(III) (0,1 -0.2 g). Add a slight excess over the calculated quantity of potassium sodium tartrate to avoid the formation of basic salts upon dilution. Dissolve approximately five times the theoretical quantity of pure pyrogallol in 100 mL of air-free water, add this all at once to the antimony solution, and dilute to 250 mL, After 30-60 seconds... 

Add dilute ammonia solution until a faint permanent turbidity is obtained and then clear the solution by careful addition of a little dilute nitric acid. To the boiling solution add a slight excess of a solution of pure pyrogallol in air-free water. Continue boiling for a short time, test for completeness of precipitation and filter. Wash the precipitate with 0.05M nitric acid and then with water. Dry at 105 °C and weigh as Bi(C6H303) (Section 11.20). 

Thus, a series of bis-cyclopentadienetitanium(III) dithiocarbamate and xanthate complexes have been prepared by Coutts et al. (49-51) by reaction of the sodium salts of the ligands with [Cp TiJCl (Cp =7r-cyclo-pentadiene) in air-free water under an inert atmosphere the dithiocarbamate complexes are bright-green, and the xanthates are blue. 

The density of mercury and pure air-free water under a pressure of 101 325 Pa(l atm) is given in units of grams per cubic centimeter (g cm-3). For mercury, the values are based on the density at 20°C being 13.545 884 g cm-3. Water attains its maximum density of 0.999 973 g cm-3 at 3.98°C. For water, the temperature °C) of maximum density at different pressures (p) in atmospheres is given by... 

Fig.2.n. Variation in threshold intensity with frequency (a) aerated water (b) air free water. 

A red microcrystalline precipitate separates and is collected on a Schlenk frit. The solid product is washed with five 20-mL portions of air-free water and dried under vacuum (0.01 torr) overnight. Yield 2.9-3.2 g [64-73% based on Ni(CO)4]. This precipitate is sufficiently pure for most synthetic purposes. Further purification is obtained by extraction in acetone (20 mL) and crystallization by dropwise addition of 2-propanol (70 mL) under stirring. 

Highly dispersed sols, containing up to 0-082 per cent, of sulphur, may be obtained 3 by passing superheated sulphur vapour, free from air, into air-free water. The sols have an acid reaction due to traces of polythionic acids and hydrogen sulphide. They are white and remain stable for several weeks. 

When superheated selenium vapour is passed into air-free water, colloidal solutions are formed which are usually rose-coloured, but at first of a blue tint and cloudy. Under the most favourable conditions clear yellowish-red or deep red sols may be obtained,4 the former being the more highly dispersed. The blue sols after dialysis are extremely stable, but non-dialysed sols decompose after a few days, selenious acid being detected except in the yellowish-red sols. The dialysed sols may be frozen to an almost colourless ice which at the ordinary temperature thaws and decomposes. The sols are negative and are readily coagulated by the addition of chlorides. 

Tim flask is now filled with a cold solution of 220g of potassium hydroxide in 1300ml of air-free water, followed by 500ml of absolute methanol and two liters of purified benzene. 

The combined orange-red aqueous extracts are added under nitrogen to a cold, well-stirred mixture of 500ml air-free water, 9% of potassium hydroxide, and 55g of the purest sodium dithlonite available (see preceding preparation). The desired product precipitates immediately and after standing for one-half hour it is filtered oil and dried for one or two days over phosphorous (V) oxide. The dry material is dissolved in absolute ether, filtered if necessary, and the solvent is removed in vacuo. Bronze colored crystals. 

Slightly soluble in air-free water soluble in alcohol, benzene, chloroform, acetone, and carbon tetrachloride. Oxidizes in air.1... 

Thus neutral water saturated with 02 is a fairly good oxidizing agent. For example, although Cr2+ is just stable toward oxidation in water, in air-saturated water it is rapidly oxidized Fe2+ is oxidized (only slowly in acid, but rapidly in base) to Fe3+ in the presence of air, although in air-free water Fe2+ is quite stable (Fe3+ + e = Fe2+, ° = +0.77 V). 

In the presence of excess of carbon dioxide free oxygen is not, according to Paul,1 essential to corrosion. As the result of several series of experiments carried out with iron in contact with air-free water and carbon dioxide, this investigator concludes that under these special conditions the reactions involved are as follow —... 

An example of a monoatomic un-ionized substrate solution is that of mercury in air-free water, which contains zero-valent mercury atoms [140],... 

Figure 1.3. Variation of the threshoid intensity with frequenoy in aerated (a) and air-free water (b). (Reproduoed with permission of Eiiis Norwood, Ref [25].)...

Osborne, Stimson, and Ginnings used the apparatus described in 14.11 with about 800 g. of air-free water in the globe. The envelope temperature was kept above the calorimeter temperature and water was evaporated, the vapour being condensed and weighed in the receiver SR (Fig. lO.II). For details of the 152 satisfactory experiments between 0° and 100° C. the original must be consulted. The results are given in the table in 12.VIII L. 

The solubility of nitrogen at I atm partial pressure in water at 0° is 23.54 ml/1, and that of oxygen is 46.89. Calculate the amount by which the freezing points of air-saturated water and air-free water differ. 

First, 240 ml. of air-free water is placed in a 1-1. nitrogen-filled three-necked flask equipped with a stirrer and a reflux condenser. Then, 110 ml. (160 g. 0.82 mol) of iron pentacarbonyl and 83 ml. (60 g. 0.59 mol) of triethylamine are added, and the mixture is stirred and heated at 80° under nitrogen for 10 hours or overnight, whichever is more convenient. It is important that the proper temperature be maintained, because below 75° the reaction is incomplete and above 90° decomposition of the iron complex occurs. 

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