Gaseous titrations

Conventional titrations may be used for various gases. The apparatus consists of a copper RV fitted with an automatic stirrer and pressure transducer. NH3/HCI has been titrated this way with a precision of 3 %. Ethylene may be used to titrate F2, and CI2/F2, CIF/Fj and CIF3/F2 mixtures. CH4/C2H6 mixtures can be titrated with F2 and alkane/alkene mixtures with CI2. 

A more spectacular gaseous titration technique is used for the estimation of the concentrations of various atomic species. This involves the use of a fast flow discharge apparatus and the spectroscopic estimation of the extent of various chemiluminescent reactions. Hydrogen and nitrogen atoms may both be titrated with NO, and oxygen atoms with N02 or the reactions being 

In reaction (55), the NO concentration is constant since it is regenerated via reaction (54). These titrations may be used to measure the concentration of these atoms in other reactions such as (56)  

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Industrial Hquid chlorine is routinely analy2ed for moisture, chlorine, other gaseous components, NCl, and mercury foUowing estabHshed procedures (10,79). Moisture and residue content in Hquid chlorine is determined by evaporation at 20°C foUowed by gravimetric measurement of the residue. Eree chlorine levels are estimated quantitatively by thiosulfate titration of iodine Hberated from addition of excess acidified potassium iodide to the gas mixture. 

Alternative variations of the isothermal titration technique utilize CO adsorption followed by reaction with gaseous 02. Experiment has shown that similar Nc values are obtained.1,19... 

The calculations for determining the pH in the titration of 1.00 liter of 0.0100 MHN03 with gaseous NH3 can be divided into 4 types ... 

It is also possible that the analyte must be calculated from a gaseous product of another reaction. In this case, one would want the gas to react with the titrant as soon as it is formed, since it could escape into the air because of a high vapor pressure. Thus an excess of the titrant would be present in a solution through which the gas is bubbled. After the gas-forming reaction has stopped, the excess titrant in this bubble flask could be titrated with the back titrant and the results calculated. This latter experiment is one form of the Kjeldahl titration. 

In order to use up the excess of bromine let a few drops (up to 0-5 c.c.) of formic acid rim down the wall of the flask, shaking vigorously meanwhile so that the bromine in the gaseous phase is also absorbed. Wait a few seconds until the solution has become decolorised and then add at once some dilute sulphuric acid and 1 -5 g. of potassium iodide. Shake, leave for five minutes, and titrate the liberated iodine with 0-1N thiosulphate solution from a micro-burette with 0 02 c.c. scale-divisions, adding starch when the colour has diminished to yellow and then continuing the titration until the colour disappears. 

Hence, in a broader-sense TT may be utilized in a number of reactions with greater efficacy, for instance complexation, precipitation, redox, neutralization. Further, TT can be used to titrate gases against other gases devoid of a liquid-phase and to titrate liquid solutions with gaseous reagents. 

Abundant evidence has been gathered to show that pure alumina, prepared either from aluminum isopropoxide or aluminum nitrate and ammonia and calcined at 600-800°, has intrinsic acidic sites. Several physical methods have been used to study the acidity of alumina. Titration with butylamine (33), dioxane (34), and aqueous potassium hydroxide (35) as well as chemisorption of gaseous ammonia (35), trimethylamine (36), or pyridine (37) gave apparent acidity values which approximated those of silica-alumina. On the other hand, the indicator method for testing the acidity of solids as developed by Walling (3S) showed no indication of even weak acids (39, 40). 

In addition to the two examples above, I have developed TKISolver models for the ideal gas, for two-component mixture concentrations, for acid base chemistry (including the generation of titration curves), for transition metal complex equilibria, for genei gaseous and solution equilibria, and for linear regression (121. 

The first two determinations by radiation absorption require accurate measurements of the extinction coefficients of ozone (a measurement of the absorption efficiency of the incoming radiation at a maximal absorption wavelength) in the ultraviolet and the infrared. Three different principles have been used over the last 20 years to measure the extinction coefficient of ozone in the ultraviolet at 254 nm manometric, decomposition stoichiometry, and gas-phase titration. The manometric method, which is based on pressure measurements of gaseous ozone, requires (in at least one case ) a substantial and somewhat uncertain correction for decomposition and the method of decomposition stoichiometry depends on the pressure change that accompanies the decomposition of ozone to oxygen, 20, 30,. Clyne and Coxon determined ozone... 

Similar titrations of gaseous HN03 with NH3 to form new NH4N04 particles and/or to enhance the growth of existing particles as the air mass passes over rural and agricultural areas have been observed in other locations as well, such as the Fraser River Valley east of Vancouver, in rural Ontario, Canada (e.g., Barthelmie and Pryor, 1998 Makar et al., 1998), and in Phoenix, Arizona (Watson et al, 1994). 

Titration. This technique provides a convenient method for following the stoichiometry of a reaction between a gas and a solution or pure liquid. Also, similar techniques can be applied to the study of gas-liquid equilibria and gas-solid equilibria. In a tensimetric titration, measured amounts of a gaseous reactant are added to a solution. After each addition a pressure measurement is made. A plot of these pressures versus the moles of added gas is then inspected for the break-point, which represents the stoichiometry of interaction (Fig. 9.4). 

New experimental data led to more severe revision of the impact mechanism concept. It appeared that the rate of the adsorbed oxygen titration by gaseous CO at high concentrations of surface oxygen (0Q) is practically independent of 60 [58, 60, 62, 108-110], i.e. the relationship... 

B) Preparation of 3-dimethylaminopropyltriphenylphosphonium bromide hydrobromide A solution of 595 grams of anhydrous dimethylamine and 1,358 grams of 3-bromopropyl-triphenylphosphonium bromide in 4 liters of ethanol is warmed to 70°C until solution is complete and the solution then is allowed to stand at room temperature for 20 hours. Volatile components are removed by distillation in a vacuum and the residue is suspended in 2.0 liters of ethanol and is redistilled to remove excess amine. The residue is dissolved in 3.0 liters of warm ethanol and gaseous hydrogen bromide is passed into the solution until the mixture is acidic. After filtration the solution is concentrated to a volume of 3.0 liters, is cooled, whereupon the product precipitates, and the precipitate is collected it weighs 1,265 grams, MP 274-281°C. Recrystallization from ethanol raises the MP to 280.5°-282.5°C. Bromide ion titration Found, 31.2% calculated 31.3%. 

A solution containing 442 g of N,N-dimethyl-3-phenyl-3-hydroxypropylamine in 5 L of chloroform was saturated with dry gaseous hydrogen chloride. 400 ml of thionyl chloride were then added to the chloroform solution at a rate sufficient to maintain reflux. The solution was refluxed an additional 5 h. Evaporation of the chloroform and other volatile constituents in vacuo yielded N,N-dimethyl-3-phenyl-3-chloropropylamine hydrochloride which was collected by filtration, and the filter cake washed twice with 1500 ml portions of acetone. The washed crystals weighed about 500 g and melted at 181°-183°C with decomposition. An additional 30 g of compound were obtained from the acetone wash by standard crystallization procedures. The structure of the above compound was verified by NMR and titration. 

The absorbing solutions are analyzed either by specific ion electrode, colorimetry, or titration depending on the analyte of interest. TABLE 2 presents a list of absorbing solutions and method of analysis for a variety of gaseous air contaminants. The overall precision and accuracy of the method depends on calibration, absorption efficiency, interferences present and time duration between collection and analysis. 

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