Ratio Of HCl Research Articles

Experimental method for preparing nanometer scale Pd probe

Two-step electrochemical etching is used to fabricate a palladium microprobe having a tip diameter less than 20 nm. The first etching is done at 4–7 V in a solution containing 4:6 volume ratio of HCl:HNO3, while in the second the etching, low voltage pulses are used.

Mechanism of thermal degradation of alternating ethylene-chlorotrifluoroethylene copolymers

Thermal degradation of the 1:1 alternating ethylene-chlorotrifluoroethylene copolymer (ECTFE) starts above 400 °C (TGA: N 2, 10 °C/min) and is characterized by elimination of HCl and HF. Structural defects in the polymer chains lead to a decrease in stability and we have observed that, in copolymers whose polyethylene sequence content had been enhanced, a low rate of dehydrohalogenation starts at about 300 °C. At the beginning, the molar ratio of HCl evolved is about twice that of HF, although the Cl to F ratio is 1:3 in the original copolymer. The HCl/HF ratio tends to 1, however, during later stages of the degradation. Infrared and ultraviolet spectroscopy indicate that the dehydrohalogenation process leads first to isolated double bonds which develop into polyene sequences of conjugated double bonds of relatively short length (<about 5 double bonds). The melt viscosity of ECTFE decreases initially when dehydrohalogenation begins, but later increases. This shows that heating induces chain scission at first while crosslinking becomes predominant with increasing double bond content. The initial dehydrohalogenation step (in which Cl is eliminated in excess of F) is likely to involve structural defects of the polymer, whereas the main dehydrohalogenation process might occur through a chain radical mechanism propagated by Cl radicals. Once the first double bond is created, the next hydrogen abstraction is likely to involve the mobile allylic hydrogen atom of the same ethylene unit from which hydrogen abstraction has already occurred. When two conjugated double bonds are thus obtained, by sequential elimination of Cl and F, the following hydrogen abstraction can occur with the same probability either from the ethylene unit next to the unsaturated structure or from any other unit in the polymer.

Airborne measurements of stratospheric constituents over the Arctic in the winter of 1989

We have used a Fourier transform spectrometer aboard the NASA DC‐8 aircraft during the Airborne Arctic Stratospheric Expedition (AASE) to record infrared absorption spectra of the polar stratosphere. From these high resolution spectra we have derived vertical column amounts above flight altitude of O3, CH4, N2O, H2O, HCl, HF, NO, NO2, ClONO2, and HNO3 for eleven flights poleward of 60°N. We report here measurements on the flight of 26 January 1989 when the flight path during the observations crossed from outside the polar vortex to inside. This allowed a clear comparison of the conditions of the air within the vortex with that outside. Observations of passive tracers such as CH4 and HF indicate that air of a certain composition within the polar vortex occurs at lower altitude than air outside. Within the vortex, we observed markedly reduced columns of HCl and NO2. The ratio of HCl to HF column dropped from its typical nidlatitude value of 4.5 to as low as 1.7 within the vortex, implying that the HCl had been chemically or physically removed from the air in the vortex. NO2 values within the vortex were near 3.0×1014 molecules‐cm−2, about a factor of two less than columns outside. In contrast to the Antarctic observations, HNO3 values were elevated within the vortex. HNO3 columns inside the vortex reached values of 30×1015 molecules‐cm−2. The ClONO2 column was largest within the vortex, peaking at 4×l015 molecules‐cm−2 near the boundary of the vortex, and decreasing farther into the vortex.

Airborne measurements of stratospheric constituents over Antarctica in the Austral Spring, 1987: 2. Halogen and nitrogen trace gases

We have used a Fourier transform spectrometer aboard the NASA DC‐8 aircraft during the Airborne Antarctic Ozone Experiment to record infrared absorption spectra of the polar stratosphere. From these high‐resolution spectra we derived vertical column amounts above flight altitude of HCl, HF, NO, NO2, ClONO2, and HNO3 for 10 flights poleward of 60°S. Within the polar vortex, where low values of total ozone are observed during the latter part of the observation period, we observed markedly reduced columns of HCl, NO2, and HNO3. HCl values in the vortex were in the range of 3–9 × 1014 molecules cm−2, compared with values around 15–20 × 1014 molecules cm−2 in mid‐latitudes and ∼30×1014 molecules cm−2 in high northern latitudes. The ratio of HCl to HF was also abnormally low, implying that the HCl had been chemically or physically removed, rather than simply being redistributed by atmospheric motion. NO2 values within the inner vortex were near 5.0×1014 molecules cm−2, about a factor of 4 less than columns outside the vortex boundary. HNO3 values were lower by a factor of 3 within the vortex, compared with a column of approximately 15×1015 molecules cm−2 outside the vortex. HNO3 columns outside the vortex are similar to northern hemisphere values. The ClONO2 column was relatively large within the vortex, peaking at ∼30×1014 molecules cm−2 near the boundary of the vortex. An upper limit of ∼8×1014 molecules cm−2 is placed on the column amount of HOCl inside the vortex.

Etude thermodynamique de la decomposition thermique des hydrates du chlorure de magnesium

The thermodynamic study of the different compounds of the system MgCl2, H2O, HCl allows to draw the stability diagram of the 8 solid phases into a three-dimensional space (temperature, total pressure and ratio of HCl and H2O partial pressures). The evolution of the composition of solid and gaseous phases during an isobaric heating is described. The conclusions of this study are in good agreement with the experimental results obtained in laboratory and with the industrial requirements set for the different steps of the dehydration of MgCl2.

Geochemical study on volcanic gases at Sakurajima Volcano, Japan

The chemical composition of volcanic gases from the summit crater of Sakurajima Volcano was observed by a variety of gas collection techniques and analytical methods, and the H2 content in gas from a hot spring was continuously measured by an automatic gas chromatograph. Increases in the molar ratio of HCl to SO2 were found to coincide with, and sometimes to precede, rises in volcanic activity. An increase in H2 content of the hot spring gas was also found to precede a period of increased volcanic activity.

Measurement of the stratospheric mixing ratio of HCl using infrared absorption technique

Approximate mixing ratios of HCl in the stratosphere have been derived from solar spectra obtained during sunset with a balloon‐borne grating spectrometer. The HCl mixing ratio increases from 0.15 × 10−9 to 1.2 × 10−9 vol HCl/vol Air in the 13.4‐27 km altitude range with a possible decrease above 27 km.

Chemical etching and fabrication of ridge waveguides on Bi12GeO20 single crystals

Chemical etching of Bi12GeO20 was investigated, and the developed technology was applied to the fabrication of ridge waveguides by an easy and rapid chemical etching method. The etching solution was prepared by mixing concentrated HCl, concentrated H2O2, and 5M NH4Cl. Ridge waveguides (0.3 mm to a few microns in size) prepared on the (110) surface had a trapezoidal cross section, and for a higher volume ratio of HCl and a longer etching time the cross section was triangular. Rectangular ridge guides were also prepared on the (100) surface, but this application is limited to small-size (several microns) ridges because with deep etching the surface is covered with etch pits and becomes rough.

A high-temperature flowing EMF cell

An EMF cell with a flowing liquid junction is described that is capable of operating at 100 atm and at temperatures up to 300 degrees C. It has no vapour space, and therefore responds quickly to changes in temperature and pressure. Fitted with H2 electrodes, the cell has given values of the dissociation product of water in KCl solutions at 0 and 50 degrees C that are correct within 0.02 in lg Qw and have a reproducibility of the same amount. Measurements of the concentration ratio of HCl in two KCl solutions from 0 to 300 degrees C have shown that the cell behaves consistently over this whole temperature range.

The Continuous Process of Ethylsilicate Manufacture

A continuous process of manufacturing Ethylsilicate (Si (OEt) 4) from EtOH and Tetrachlorosilane (SiCL4) was developed.This reaction is the rapidly consecutive reaction, remarkably exothermic, and generating a large quantity of HCL. Furthermore, the formation of the byproduct (polysilicate) increases when the reaction temperature rises above 0°C, and therefore there must be rigid control of the reaction temperature. From thermodynamic calculation, it was concluded that the calolification in the reaction was almost all caused by the heat of the solution of HCl in unreacted EtOH. When EtOH containing the suitable quantity of HCl is used, the calolification in reaction is not evolved.Basing upon this conclusion, the continuous process was developed and carried out on a small pilot plant scale using EtOH-HCl. Reactor consisted of two stages, the first was a jet pump, and the second a stirred tank.Data showing the effect of flow ratio (EtOH/SiCl4) and concentration of HCl in EtOH on the yields of Si (OEt) 4 were presented. From these results, the optimum condition was determined and the cost of production of this continuous process compared with that of the former batch process.