Hydrogen-oxygen Flame Research Articles

Qualitative atomic emission solution analysis using a visible-region spectrometer

This experiment is part of our Level 2 (3rd year) practical course in analytical chemistry. Its purpose is to give students an appreciation of qualitative and to some extent quantitative, atomic emission spectroscopy without the complication of photographic spectrography or the sophistication of multielement direct reading spectrometry. Solutions of LiC1 (0,1%), NaC1 (0.1%), KC1 (1.0 %), CsCI (1.0 %), CaC12 (1.0 %), SrCI2 (1.0 %), and BaC12 (1.0%) containing the indicated (w/v) metal concentrations are nebulised into a hydrogen-oxygen flame using a Hilger and Watts flame emission device designed originally as an attachment for use with the Uvispek but used here with their D187 constantdeviation spectrometer. Students first set the wavelength drum accurately on the sodium doublet at 589.6 nm, at the same time exploring the importance of correct focusing and the effect of slitwidth on resolution. They then spray the other solutions and note the main spectral features of each. The potassium and caesium emissions are hard to see and hopefully give the student an idea of the compromise between detector response and resolution. The difference between line spectra and the band spectra of alkaline earth metaloxygen species is splendidly apparent. The flame is so hot that some of the less familiar line emissions of the alkali metals can be seen. Finally students analyse an unknown solution (0.5 ~ Ca 2 +, 0.5 % Sr 2 +, 0.5 ~ Ba 2 +) and differentiate between LiC1 (0.02 %) and SrC12 (1.0 %) solutions, this latter being a notable success of early spectroscopic endeavour. In addition students may point the spectrometer at a window to observe Fraunhofer lines and the wavelength limits of the visible daylight spectrum.

Rotational Raman scattering from premixed and diffusion flames

Use of rotational Raman spectroscopy as a flame probe is examined. Results of rotational and vibrational Raman scattering from hydrogen oxygen, methane-air and propane-air flames are presented. Time-averaged temperatures are measured, both below and above the inner cones of the premixed flames, based upon rotational Raman scattering from the major species (N 2, O 2, H 2 and CO 2). Corrections for vibrational-rotational interactions and for the effects of rotational transitions from vibratinally excited molecules are included in the temperature calculations. For hydrogen or methane flames, temperatures based upon rotational Raman scattering from N 2 or O 2 have lower uncertainties (1–4%) than those based upon vibrational Raman scattering (3–9%) because rotational Raman transitions are generally more intense and give rise to many more transitions. Scattering from CO 2, H 2O, or C 3H 8 does not seriously interfere with rotational Raman temperature measurements in the flames studied. It is concluded that rotational Raman spectroscopy can be a useful nonperturbing probe of concentrations and temperatures in atmospheric pressure flames. Rotational Raman intensity factors relative to N 2, are obtained from room temperature pure rotational Raman spectra to be 2.61 ± 0.13 for O 2 and 0.20 ± 0.05 for HCl.

Near-limit downward propagation of hydrogen and methane flames in oxygen [sbnd]nitrogen mixtures

Measurements are reported on nitrogen concentrations required to prevent downward propagation of hydrogen oxygen and methane oxygen flames in open tubes of 2.5 and 5.1 cm diameter. Limits plotted as functions of the fuel oxygen ratio show that quenching is most difficult the fuel-lean side for hydrogen flames and near stoichiometric for methane flames. Cellular patterns were observed near flammability limits, and near-limit flame speeds were measured. Results are interpreted mainly in terms of conductive losses from cellular flames since alternative mechanisms appear to produce qualitatively inconsistent predictions.

Higher ro-vibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 6200 and 9100 cm-1

The spectra of hydrogen-oxygen and acetylene-oxygen flames have been recorded on a Fourier transform spectrometer in the region 6200–9100 cm-1 with a resolution of 0·015 cm-1. In this region, we have performed a detailed analysis of the 2v 2 + v 3, v 1 + v 3, v 1 + v 2 + v 3 - v 2 and v 1 + v 2 + v 3 bands. A primary motive for this study was to obtain higher rotational energy levels for the (021), (101) and (111) vibrational states. Moreover an extensive set of rotational levels of the (010) vibrational state has been deduced from the combined study of hot bands involving the (011), (021) and (111) vibrational states. A room-temperature absorption spectrum of water recorded on a Fourier transform spectrometer in the region 1750–2300 cm-1 (resolution 0·005 cm-1) has also been used to confirm the analysis.

Measurement of the concentration of hydrogen atoms in a hydrogen-oxygen flame at atmospheric pressure

Measurement of the concentration of hydrogen atoms in a hydrogen-oxygen flame at atmospheric pressure

The Transition to Instability in a Steady Hydrogen-Oxygen Diffusion Flame

Abstract —Blow-off of a streamwise diffusion flame does not usually show features intermediate between those characteristic of the burner-attached flame and a quasi-stable lifted flame. The present work has, however, characterised an unusual intermediate stage in the blow-off of a lean hydrogen-oxygen diffusion flame, where the flame base takes on a stable cellular structure. From previous work, it is known that, near extinction, there is transfer of fuel through the base of the flame into the oxidant stream. The partial premixing resulting from such inter-stream transfer gives rise in the particular case of this lean flame to a composite premixed/diffusion flame structure at the flame base which is most probably responsible for the cellularity.

Thermochemical reactions of aluminum and fluorine in hydrogenoxygen flames

The thermodynamic properties of reactions of aluminum and fluorine compounds in high temperature hydrogenoxygen flames were determined employing a specially designed four-stage differentially pumped vacuum-mass spectrometer system. Investigation of the chemical equilibria involved established the reaction enthalpies for these high temperature stable species. The thermochemical reactions of the aluminum and fluorine species with the H 2 O 2 flame molecules produced the major species AlO, AlO 2, HAlO, FAlO, HOAlO and AIF. The heats of formation at 298°K were 18.5 ± 5, −41.6 ± 5, −40.0 ± 5, −90.0 ± 5 and −135.0 ± 5 kcal/mole for AlO(g), AlO 2(g), HAlO(g), HALO(g), HOAlO(g), and FAlO(g), respectively. The bond energy for AlO was found to be in agreement with those previously determined from thermochemical and spectroscopic studies. The investigation also disclosed that the energy of the OF bond is insufficient to form stable OF species in the flame, and that the major species involving fluorine and oxygen with aluminum is structured as FAlO.

Higher ro-vibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 2800–6200 cm-1

Hydrogen-oxygen flame spectra have been recorded from 2850 cm-1 to 6200 cm-1 with a high resolution Fourier transform spectrometer at a limit of resolution of about 0·015 cm-1, and the emission spectrum of hot water vapour has been obtained. The complete analysis of the v 1, v 3 and v 2 + v 3 bands has been performed. A large set of new higher rotational energy levels for the (000), (100), (001) and (011) vibrational states is reported. A discussion of the assignment problem and of the least squares method for deriving the energy levels from the observed transitions is detailed.

Evaluation of the Contribution of Organic Solvent Species toward Signal Enhancement in the Premixed Oxygen-Hydrogen Flame

Studies conducted in premixed oxygen-hydrogen, oxygen-acetylene, and nitrous oxide-acetylene flames utilizing a relatively small drop size aerosol generated with high frequency ultrasonic nebulization indicate that under the proper conditions emission signal enhancements observed with methanol can be attributed primarily to both increased rate of nebulization and the presence of additional reducing species. However, under the fuel-rich conditions commonly employed for analysis, solvent-supplied reducing species were found to be of primary significance only in the case of the premixed oxygen-hydrogen flame.

Analysis of a laminar flat plate boundary-layer diffusion flame

A numerical analysis of a laminar hydrogen-oxygen diffusion flame in a flat plate boundary layer was carried out in order to investigate its non-equilibrium and close-to-equilibrium structure at various positions in the boundary layer. Variable properties including thermodiffusion and 15 elementary reactions between 8 species were used in the calculation. The results show the ignition and non-equilibrium development of the flame and the approach to local chemical equilibrium within the flame zone. On both sides of the flame zone, due to the low temperatures there, the chemical reactions are practically frozen even at large distances from the leading edge.

Improvements in flame emission spectrometry through the use of ultrasonic nebulization into a premixed oxygen-hydrogen flame

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTImprovements in flame emission spectrometry through the use of ultrasonic nebulization into a premixed oxygen-hydrogen flameD. E. Gutzler and M. B. DentonCite this: Anal. Chem. 1975, 47, 6, 830–833Publication Date (Print):May 1, 1975Publication History Published online1 May 2002Published inissue 1 May 1975https://doi.org/10.1021/ac60356a033RIGHTS & PERMISSIONSArticle Views42Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (423 KB) Get e-Alerts Get e-Alerts

Determination of fluorine in boron-containing materials with a fluoride sensitive electrode

The fluoride-ion selective micro-determination of fluorine in organic materials after closed flask combustion is an established technique. Interferences, due to complexation of the fluoride ion can occur, if the sample contains boron or fluorborate ion. This paper describes a method that avoids complexation of fluoride by combustion in a hydrogen-oxygen flame and absorption of the resulting H2F2 in alkali hydroxide solution. By this method, samples can be analyzed for fluorine without interference by boron. Some results of the analysis of pharmaceutical materials are given.

Structure in methane-oxygen diffusion flames

The fine structure of a methane-oxygen diffusion flame is discussed in the light of perturbation techniques already developed and applied to hydrogen-oxygen flames. The flame model is supported by a modestly realistic chemical kinetic scheme comprising ten reactions and is investigated in circumstances of reaction-broadening. The competition between reaction and mass diffusion which determines reaction zone structure is revealed to be particularly sensitive to the choice of reactions describing methyl radical removal. The structure predicted on the assumption that the reaction between methyl radicals and oxygen atoms predominates is revealed to be incompatible with concentration measurements of stable species and radicals made on a Wolfhard-Parker burner. In particular, predictions regarding methyl radical concentration, reaction zone thickness and the extent of reaction zone penetration by methane are not substantiated. The inclusion of reactions of methyl with hydroxyl and molecular oxygen does, however, lead to diffusion flame structure consistent with experiment and similar in many respects to that of the hydrogen-oxygen flame. Some ambiguity remains in respect of some detailed aspects of fuel-rich structure.

The “point source” technique using upstream sampling for rate constant determinations in flame gases

The “point source” technique has been extended to both the direct and relative measurement of first-order and pseudo-first-order reaction rates using flames as high-temperature radical baths. Apparatus and technique are described and critically discussed. Measurements of the concentrations of trace gas injected from a point source into a laminar stream were made upstream from the point of injection in order to eliminate the dependence on flow velocity information. The afterburning region of a hydrogen-rich hydrogen-oxygen flame provided a laminar stream containing hydrogen atoms. Using a pseudo-first-order model, rate constants and rate constant ratios were measured in the temperature range 870–1088K. Two independent methoes were used in the data analysis to get measures of absolute rates and rate ratios. Specifically measured were the rate constants k (H + CH 3 Br), k (H + CH 3 Cl), and k (H + CH 3 F) as well as the rate constant ratios k (H + CH 3 Br)/ k (H + CH 3 F), k (H + CH 3 Br)/ k (H + CH 3 Cl), and k (H + CH 3 Cl)/ k (H + CH 3 F). By combining our results with previous work, the constants were evaluated over the temperature range 300–1088K.

Spectrometric properties and analytical applications of premixed oxygen-hydrogen flames

Spectrometric properties and analytical applications of premixed oxygen-hydrogen flames

A mass spectrometric investigation of reactions involving tungsten and molybdenum with potassium-seeded H 2/O 2 flames

The formation of the compounds KHMoO 4 , K 2 MoO 4 , KHWO 4 and K 2 WO 4 was established by mass spectrometric studies in atmospheric hydrogen-oxygen flames containing potassium. Thermodynamic data for these compounds were obtained by studying the reactions K(g) + H 2 MoO 4 (g) = KHMoO 4 (g) + H(g), 2K(g) + H 2 MoO 4 (g) = K 2 MoO 4 (g) + 2H(g), K(g) + H 2 WO 4 (g) = KHWO 4 (g) + H(g), 2K(g) + H 2 WO 4 (g) = K 2 WO 4 (g) + 2H(g). The heats of formation, ΔH f 298K , obtained for the species KHMoCO 4 (g), K 2 MoO 4 (g), KHWO 4 (g) and K 2 WO 4 (g) were −243.0 ± 5, −272.5 ± 5, −257.4 ± 4 and −278.2 ± 5 kcal/mole, respectively.

Preparation in a hydrogen-oxygen flame of ultrafine metal oxide particles. Oxidative properties toward hydrocarbons in the presence of ultraviolet radiation

Divided metal oxides (Al 2O 3, Fe 2O 3, GeO 2, SiO 2, TiO 2, V 2O 5, ZrO 2) are prepared by carrying vapor of metal chloride into the flame of an oxygen-hydrogen burner. Collected oxide particles do not have internal porosity and exhibit a nearly constant diameter in the range of 100–2000 Å. The geometry of these particles and their crystalline structure depend on the flame temperature, the flow rate of carrier gas, and the linear velocity of the chloride vapor in the burner. Binary, ternary, or doped oxides may also be prepared by this method from the appropriate mixture of metal chlorides. Oxygen at 25°C is adsorbed on some oxides, in particular on TiO 2, in the presence of uv radiation, as a labile species O 2 − which reacts with paraffins, olefins, CO, SO 2, and NO, under irradiation, to give products of partial or total oxidation. The registered quantum yield is equal to one for wavelengths not exceeding 3400 Å. The reactivity of O 2 − species toward isobutane is investigated by ESR for different wavelengths.

Raman Scattering from Flames

Laser Raman scattering data for nitrogen, oxygen, and water vapor have been obtained from hydrogen-air and hydrogen-oxygen flames. The resulting ground-state and upper-state vibrational bands exhibit strong asymmetrical broadening. Experimental spectral profiles have been fitted theoretically to give a new measurement technique for the determination of rotational and vibrational excitation temperatures.

The Hydrocarbon-induced Fluorescence of Atoms in Flames

The phenomenon of chemiluminescent emission from atoms introduced into hydrocarbon flames has been studied in a basic hydrogen-oxygen diffusion flame at low hydrocarbon concentrations. Emissions from several atoms are first order in methane concentration and examination of the relative populations of the excited states of arsenic suggests a single excitation mechanism with available energy in excess of 8.5 eV. Previously proposed mechanisms are discussed and the available evidence favors the process[Formula: see text]as the origin of the energy of excitation.

Experimental and mathematical study of a hydrogen-oxygen flame

Fuel-rich premixed hydrogen-oxygen flames were stabilized on cooled porous plate burners at pressures around 10 mm Hg. The concentrations of H 2 , O 2 , H 2 O, H, and OH were measured by means of mass spectroscopy, gas chromatography, uv-absorption spectroscopy, and ESR spectroscopy. For one flame, the system of equations describing the propagation of the flame was solved numerically with respect to the interactions between the flame and the flameholder. These profiles, which were computed according to the boundary conditions and the kinetic data, are in agreement with the measured profiles. A discussion on the accuracy of concentration and temperature measurements is given, taking into account diffusion, thermal diffusion, heat transfer, and “two-body collision” equilibrium. From the experimental and mathematical work, it was found that, in these fuel-rich hydrogen-oxygen flames, water is produced at low temperatures by the chain mechanism H+O 2 +M→HO 2 +M H+HO 2 →OH+OH OH+H 2 →H 2 O+H, with the chain length of the order of 10. At high temperatures, water is produced by the branching mechanism H+O 2 →OH+O (2) O+H 2 →OH+H OH+H 2 →H 2 O+H (1) The derived rate coefficients k 1 =1×10 13 exp (−4800/ RT ); 500°K T k 2 =2.3×10 14 exp (−16800/ RT ); 650°K T 3 , °K) are in good agreement with rate constants reported in the literature.