Silver vapor

Codeposition of silver vapor with perfluoroalkyl iodides at -196 °C provides an alternative route to nonsolvated primary perfluoroalkylsilvers [272] Phosphine complexes of trifluaromethylsilver are formed from the reaction of trimethyl-phosphme, silver acetate, and bis(trifluoromethyl)cadmium glyme [755] The per-fluoroalkylsilver compounds react with halogens [270], carbon dioxide [274], allyl halides [270, 274], mineral acids and water [275], and nitrosyl chloride [276] to give the expected products Oxidation with dioxygen gives ketones [270] or acyl halides [270] Sulfur reacts via insertion of sulfur into the carbon-silver bond [270] (equation 188)... 

Fig. 7. The optical spectra obtained on depositing (A) silver vapor with methane at 10-12 K at Ag CH4 = 1 10, and (B) silver vapor with water vapor at 10-12 K at Ag HjO = 1 10, brief warming to 77 K, and recooling to 10-12 K for spectral recording (146).

Fig. 8. The optical spectra obtained on depositing silver vapor with n-Ct2H< vapor at 10-12 K, and (A) Ag n-CuHu 1 10<, (B) Ag n-CttH = 1 rlO , and (C)-(E) showing the progress of annealing (B) at 30, 40, and 80 K, respectively (146).

Silver vapor cocondensed with matrices of HjO or paraffin wax (C22H4 ) at 12 K gives mainly an atomic dispersion of Ag. However when these Ag atom matrices are warmed briefly (to 77 K for HjO and up to 80 K for C22H46), thermal diffusion takes place with aggregation of the Ag atoms into small clusters of up to Ag4. These thermal aggregation methods can be used to prepare small clusters, but a mixture of metal polymers is usually obtained. 

A quantitative measurement of the depth of penetration of the diffracted electrons has been made previously by the author (1) by depositing silver vapor onto a gold crystal surface, using a calibrated silver source. Since the lattice structures are the same and the lattice constants differ by less than 0.4%, the silver was found to deposit as a thin crystal on the gold surface. Because of the different indices of refraction and certain fine-structure characteristics for the two metals, the diffraction beams from silver and gold were readily distinguished. 

The molar heats of fusion and vaporization for silver are 11.3 kJ/mol and 250. kJ/mol, respectively. Silver s normal melting point is 962 °C, and its normal boiling point is 2212 °C. What quantity of heat is required to melt 12.5 g of silver at 962 °C What quantity of heat is liberated when 4.59 g of silver vapor condenses at 2212 °C ... 

Fig. 2 (Left) SEM images of silver vapor deposited on a ZnSe window with the nominal thickness measured with a quartz mierobalance the Ag islands are well separated in the 5-nm thick layer but are close to the pereolation limit in the 10-nm layer. (Right) SEIRA transmission spectra of PNTP for the 5-nm layer (dotted line) and the 10-nm layer (solid line). [In part reprinted from Band shapes in the infrared spectra of thin organic films on metal nanoparticles D. A. Heaps and P. R. Griffiths, Vibrational Spectrosc., 2006,42(1), 45-50 copyright 2006, with permission from Elsevier.]...

A sample of 113 L of helium gas at 1360 "C and prevailing barometric pressure is passed through molten silver at the same temperature. The gas becomes saturated with silver vapor, and the liquid silver loses 0.120 g in mass. What is the vapor pressure of liquid silver at 1360 °C ... 

Let s assume that after the gas has become saturated with silver vapor, its volume remains at 113 L. This assumption will be valid if the vapor pressure of the silver is quite low compared with the barometric pressure. According to Dalton s law of partial pressures (page 215) we can deal with the silver vapor as if it were a single gas occupying a volume of 113 L. 

The fixed points in the lTS-90 are given in Tabie 11.39. Platinum resistance thermometers are recommended for use between 14 K and 1235 K (the freezing point of silver), calibrated against the fixed points. Below 14 K either the vapor pressure of helium or a constant-volume gas thermometer is to be used. Above 1235 K radiometry is to be used in conjunction with the Planck radiation law,... 

From Ethyl Alcohol. Some acetaldehyde is produced commercially by the catalytic oxidation of ethyl alcohol. The oxidation is carried out by passing alcohol vapors and preheated air over a silver catalyst at 480°C (98). 

Aqueous formaldehyde is corrosive to carbon steel, but formaldehyde in the vapor phase is not. AH parts of the manufacturing equipment exposed to hot formaldehyde solutions must be a corrosion-resistant alloy such as type-316 stainless steel. Theoretically, the reactor and upstream equipment can be carbon steel, but in practice alloys are required in this part of the plant to protect the sensitive silver catalyst from metal contamination. 

Mercury amalgamates readily with gold and silver, and systems have been developed using these metals distributed on various carriers to remove mercury vapor from an akstream. When the system is saturated, the mercury can be removed easily and recovered by heating the unit and condensing the mercury. Other metals, such as copper and 2inc, can also be used. 

Spectroscopic. The electronic configuration of Pu vapor is [Xe] The earliest studies of copper- and silver-spark spectra... 

Potassium, a soft, low density, silver-colored metal, has high thermal and electrical conductivities, and very low ionization energy. One useful physical property of potassium is that it forms Hquid alloys with other alkah metals such as Na, Rb, and Cs. These alloys have very low vapor pressures and melting points. 

Bromine reacts with essentially all metals, except tantalum and niobium, although elevated temperatures are sometimes required, eg, soHd sodium does not react with dry bromine but sodium vapor reacts vigorously. Metals such as lead, magnesium, nickel, and silver react with bromine to form a surface coat of bromide that resists further attack. This protective coating allows lead and nickel to be used as linings in bromine containers. Metals tend to be corroded by bromine faster in the presence of moisture than without, probably because of the formation of hydrobromic and hypobromous acids. 

---