M.A. Beg

Studies on silver tungstate-mercuric lodide reaction in solid state

Abstract The kinetics and mechanism of reaction of silver tungstate with rhombic and tetragonal mercuric iodide in solid state have been studied using X-ray diffraction, chemical analysis, and electrical conductivity measurements. The reaction is diffusion controlled and the data for lateral diffusion best fit the equation X n = kt . Activation energies suggest that rhombic HgI 2 is more reactive toward Ag 2 WO 4 than its tetragonal form. The reaction rate that rises abruptly near the transition temperature records a smooth rise with increase in temperature both below and above this temperature.

Formation of metal chelates in solid state reaction between 8-hydroxyquinoline and carbonates of cadmium and zinc

Abstract The solid state reactions between 8-hydroxyquinoline (8-HQ) and CdCO 3 and ZnCO 3 have been studied. The Brounshtein-Ginstling rate equation is followed in both cases. The activation energy for CdCO 3 -8-HQ and ZnCO 3 -8-HQ are respectively 92.3 ± 3.3 and 86.6 ± 0.6 kJ mole −1 . The reaction products were characterized by elemental analysis, X-ray diffraction, and IR studies. Metal (Zn and Cd) carbonates and 8-HQ react in 1:2 molar ratio and the reaction proceeds via surface migration of 8-HQ.

Kinetics and mechanism of solid state reactions of silver tungstate with mercuric bromide and mercuric chloride

Abstract The kinetics and mechanism of the Ag 2 WO 4 HgBr 2 and Ag 2 WO 4 HgCl 2 reactions have been studied in the solid state. The kinetics have been carried out by a visual technique. Both the reactions follow the parabolic rate law X 2 = Kt , where X is the thickness of product layer at time t and K is the parabolic rate constant. The kinetics have been studied at several temperatures, for different lengths of air-gap between the two reactants and for different particle sizes of the reactants. It has been demonstrated that diffusion in both the reactions is predominantly controlled by the vapour phase, but diffusion by surface migration is also significant. In order to understand the mechanism of the reactions, X-ray powder diffraction, chemical analysis, conductivity and thermal studies have been carried out. Silver tungstate reacts with mercuric bromide and mercuric chloride in the molar ratio 1:1 to give AgBr, HgWO 4 and AgCl, HgWO 4 , respectively, as the end products.

Kinetics and mechanism of reactions of silver tungstate with mercuric bromoiodide and mercuric chlorobromide in the solid state

Abstract The kinetics and mechanism of the Ag 2 WO 4 -HgBrI and Ag 2 WO 4 -HgClBr reactions were studied by X-ray diffraction, thermal and electrical conductivity measurements. The kinetics were studied at several temperatures and for different lengths of air- gap between the two reactants. The kinetic data fit the equation X n = Kt , where X is the thickness of the product layer at time t and n and K are constants. Silver tungstate reacts with mercuric bromoiodide and mercuric chlorobromide in the molar ratio 1:1 to give Ag(Br,I), HgWO 4 and Ag(Cl,Br), HgWO 4 , respectively, as the end products.

Cyclic transport of Fe3+ as H[FeCl4] and H[FeBr4] through a dibutyl ether-benzene membrane

Abstract Cyclic transport of Fe 3+ as H[FeX 4 ], where X is Cl or Br, across solvent-type liquid membranes has been demonstrated. H[FeCl 4 ] was transported from HCl into HBr across a dibutyl ether—benzene mixture. In HBr the transported species reacted to H[FeBr 4 ], which moved out to the HCl side against the concentration gradient of Fe 3+ . On the HCl side it was reconverted into H[FeCl 4 ]. This continued till equilibrium was achieved. Likewise, Fe 3+ , present as H[FeBr 4 ] in HBr, migrated from HBr into HCl and then back to HBr across the same membrane.

HgCl2AgI reaction in solid state

Abstract Ag HgClI2 and Ag HgCl2I were obtained by the interaction of HgCl2 and AgI in the solid state at 100°C. A diffusion-controlled HgCl2AgI reaction proceeds via counterdiffusion of Ag+ and Hg2+ and its activation energy is 23.90 kcal/mole. At the start, the process is surface or grain boundary diffusion-controlled having an activation energy of 8.32 kcal/mole. Different molar ratios of the reactants gave rise to different end products. The reaction was followed by X-ray, chemical analysis, thermal, conductivity measurements. Evidence for the formation of solid solution between Ag2HgI4 and AgCl is reported.

Kinetics and mechanism of reaction between silver molybdate and mercuric iodide in solid state

The kinetics and the mechanism of the reaction between silver molybdate and mercuric iodide were studied in the solid state by X-ray, chemical analysis, and electrical conductivity measurements. This is a multistep reaction where Ag2HgI4 is formed as an intermediate. In an equimolar mixture of Ag2MoO4 and HgI2, AgI and HgMoO4 are formed, whereas in a 1:2 molar mixture Ag2HgI4 and HgMoO4 are formed. The data for lateral diffusion best fit the equationXn = kt, whereX is the product thickness, t is time, andk andn are constants. This is a multistep solid state ionic reaction initiated by the diffusion of HgI2 molecules as such and not through counterdiffusion of cations.

Solid-state reaction between silver molybdate and mercuric chlorobromide

Abstract The reaction between silver molybdate and mercuric chlorobromide in solid state was followed by X-ray powder diffraction, chemical analysis, and thermal and electrical conductivity measurements. Kinetics of reaction were studied in detail using a visual technique. Diffusion coefficients of HgClBr were determined. The process is reaction controlled at low temperatures while at high temperatures it is diffusion controlled. Ag 2 MoO 4 and HgClBr react in solid state in an equimolar ratio and the reaction proceeds via vapor phase diffusion controlled mechanism.