Gold in water

Table 11 Coupling of aldehydes, alkynes, and amines catalyzed by gold in water...

Fig. 4. Calculated spectra using Eq. (15) for the extinction cross section of 5 nm silica particles coated with shells of 0.2 to 4.0 nm of gold in water...

Solids may dissolve in complexing agents with a change in valence state (so it is debatable whether such reactions should be classified as simple addition). In the case of the dissolution of metallic silver or gold in water in the presence of cyanide ion, the oxygen of the air acts as the oxidizing agent ... 

Dissolving AU2O3 in neat CH3CO2H forms Au acetate, but this rapidly decomposes to metallic gold in water. 

Liu ZP, Jenkins SJ, King DA Origin and activity of oxidized gold in water-gas-shift catalysis, Phys Rev Lett 94(19) 196102, 2005. 

Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group and is the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet. Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineral oil or in a vacuum or inert atmosphere. 

Patterns of ordered molecular islands surrounded by disordered molecules are common in Langmuir layers, where even in zero surface pressure molecules self-organize at the air—water interface. The difference between the two systems is that in SAMs of trichlorosilanes the island is comprised of polymerized surfactants, and therefore the mobihty of individual molecules is restricted. This lack of mobihty is probably the principal reason why SAMs of alkyltrichlorosilanes are less ordered than, for example, fatty acids on AgO, or thiols on gold. The coupling of polymerization and surface anchoring is a primary source of the reproducibihty problems. Small differences in water content and in surface Si—OH group concentration may result in a significant difference in monolayer quahty. Alkyl silanes remain, however, ideal materials for surface modification and functionalization apphcations, eg, as adhesion promoters (166—168) and boundary lubricants (169—171). 

Stannous Oxide. Stannous oxide, SnO ((tin(II) oxide), mol wt 134.70, sp gr 6.5) is a stable, blue-black, crystalline product that decomposes at above 385°C. It is insoluble in water or methanol, but is readily soluble in acids and concentrated alkaHes. It is generally prepared from the precipitation of a stannous oxide hydrate from a solution of stannous chloride with alkaH. Treatment at controUed pH in water near the boiling point converts the hydrate to the oxide. Stannous oxide reacts readily with organic acids and mineral acids, which accounts and for its primary use as an intermediate in the manufacture of other tin compounds. Minor uses of stannous oxide are in the preparation of gold—tin and copper—tin mby glass. 

Despite this detailed familiarity with equilibrium, there is one facet we have not considered at all. What determines the equilibrium constant Why does one reaction favor reactants and another reaction favor products What factors cause sodium chloride to have a large solubility in water and silver chloride to have a low solubility Why does equilibrium favor the reaction of oxygen with iron to form FejAi (rust) but not the reaction of oxygen with gold As scientists, we cannot resist wondering what factors determine the conditions at equilibrium. 

Photodissociation of Diiodoethane Hydrodynamics of Laser-Heated Liquids Gold Nanoparticles in Water... 

These P-CD/adamantyl pseudorotaxane-terminated dendrimers can be used as nanoreactors in the preparation of gold and platinum nanoparticles in water... 

Lyotropic liquid crystalline nanoparticles have also been described. Concentrated solutions of gold nanorods in water in the presence of a surfactant (cetyltrimethyl-ammonium bromide) display a nematic mesophase stable up to 200 °C [74[. The N mesophase was identified by optical microscopy by their typical nematic droplets texture. 

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