Aluminum volatile elements

The chemical compositions of individual chondrules have been determined by neutron activation of extracted samples or by electron microprobe analyses of chondrules in situ. Some, but not all chondrules are depleted in moderately volatile elements. There is a compositional continuum between the olivine-rich and aluminum-rich chondrules. Original concentrations of the short-lived radionuclide 26A1 in chondrules suggest they formed very early, before all of this isotope decayed, but as much as 2-5 million years after the formation of CAIs (see Refractory Inclusions, below). 

Ma (Wadhwa et al. 2007 and references therein), which is actually the age of a group of inclusions within chondrites known as calcium-aluminum-rich inclusions (CAIs). The word primitive refers to the fact that the bulk compositions of all chondrites, within a factor of two, are solar in composition for all but the most volatile elements (Weisberg et al. 2006). This fact indicates that chondrites have not been through a planetary melting or differentiation process in their parent body, indicating that they have recorded the materials that were present and the processes that operated within the disk before or during planet formation. 

An Ej value of greater than one represents enrichment of element i in the sample as compared to the reference whereas a value less than one means depletion. In order to avoid possible confusion, sample and reference names can be added after j. As shown in Figure 1(a), the average shale composition is very similar to that of the upper continental crust (Ej i = 1.0 0.3). The obvious exceptions are Li, and volatile elements B, C, N, S, Se, Te, Br, I, As, Cd, In, Sb, Hg, and Bi, which are enriched in the shale in comparison to the upper continental crust when aluminum is chosen as the normalizing element (Li, 2000). These excess volatile elements came from the interior of the Earth by magmatic... 

DM0 composite growth from aluminum alloys that contained no Mg but other, alternative volatile elements (Na, Li, Zn). In each case DMO growth occurs at temperatures for which the vapor pressure of the volatile solute is an appreciable fraction of the partial pressure of oxygen in the gas phase. 

The iodides of the alkaU metals and those of the heavier alkaline earths are resistant to oxygen on heating, but most others can be roasted to oxide in air and oxygen. The vapors of the most volatile iodides, such as those of aluminum and titanium(II) actually bum in air. The iodides resemble the sulfides in this respect, with the important difference that the iodine is volatilized, not as an oxide, but as the free element, which can be recovered as such. Chlorine and bromine readily displace iodine from the iodides, converting them to the corresponding chlorides and bromides. 

The last reaction is the most favored of these three. The actual occurrence of the reactions with elemental phosphorus or phosphorous trichloride as products has been explained to be due to kinetic reasons. The thorium present in the ore volatilizes in the form of thorium tetrachloride (ThCl4) vapor other metallic impurities such as iron, chromium, aluminum, and titanium also form chlorides and vaporize. The product obtained after chlorination at 900 °C is virtually free from thorium chloride and phosphorous compounds, and also from the metals iron, aluminum, chromium, and titanium. 

Next, let the example of vanadium, which, in the as-reduced condition, may contain a variety of impurities (including aluminum, calcium, chromium, copper, iron, molybdenum, nickel, lead, titanium, and zinc) be considered. Vanadium melts at 1910 °C, and at this temperature it is considerably less volatile than many of the impurity metals present in it. The vapor pressure of pure vanadium at this temperature is 0.02 torr, whereas those of the impurity elements in their pure states are the following aluminum 22 torr calcium 1 atm, chromium 6 torr copper 23 torr iron 2 torr molybdenum 6 1CT6 torr nickel 1 torr lead 1 torr titanium 0.1 torr and zinc 1 atm. However, since most of these impurities form a dilute solution in vanadium, their actual partial pressures over vanadium are considerably lower than the values indicated. Taking this into account, the vaporization rate, mA, of an element A (the evaporating species) can be approximated by the following free evaporation equation (Langmuir equation) ... 

In addition to the ability to react nonspecifically with hydrocarbons, active nitrogen can readily participate in energy transfer reactions with volatile organometal-lic compounds, leading to atomic emission from the metal atom. By use of appropriate optical filters, selective detection of elements such as aluminum, lead, tin, and mercury has been achieved in the presence of large excesses of organics [58],... 

The bomb method for sulfur determination (ASTM D129) uses sample combustion in oxygen and conversion of the sulfur to barium sulfate, which is determined by mass. This method is suitable for samples containing 0.1 to 5.0% w/w sulfur and can be used for most low-volatility petroleum products. Elements that produce residues insoluble in hydrochloric acid interfere with this method this includes aluminum, calcium, iron, lead, and silicon, plus minerals such as asbestos, mica, and silica, and an alternative method (ASTM D1552) is preferred. This method describes three procedures the sample is first pyrolyzed in either an induction furnace or a resistance furnace the sulfur is then converted to sulfur dioxide, and the sulfur dioxide is either titrated with potassium iodate-starch reagent or is analyzed by infrared spectroscopy. This method is generally suitable for samples containing from 0.06 to 8.0% w/w sulfur that distill at temperatures above 177°C (351°F). 

The compound of chlorine with the combustible element of the clay (aluminum chloride) is volatile at a temperature which is not much above that of boiling water, it is somewhat yellowish, perhaps however from admixed carbon it is soft, but still has crystalline form, it absorbs water with avidity and dissolves therein with great ease and with evolution of heat. Rapidly heated with potassium amalgam, it is decomposed, potassium chloride and aluminum amalgam being formed. This amalgam is very quickly decomposed in contact with the atmosphere By distillation without contact with the... 

Toxicity Variable. The hydrides of phosphorus, arsenic, sulfur, selenium, tellurium and boron which are highly toxic, produce local irritation and destroy red blood cells. They are particularly dangerous because of their volatility and ease of entry into the body. The hydrides of the alkali metals, alkaline earths, aluminum, zirconium and titanium react with moisture to evolve hydrogen and leave behind the hydroxide of the metallic element. This hydroxide is usually caustic. See also sodium hydroxide... 

Aluminum and calcium can become volatile if they form hydroxides. Depletions of these elements compared to others with similar volatility in a gas of solar composition can help us to investigate the redox conditions under which certain objects formed. 

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