Analyzing a Mixture

Consider an 80 20 mixture (by weight) of potassium perchlorate and titanium (KClOyTi). Assume that you have 100 grams for calculation purposes. You do not need to balance the equation to perform this analysis. 

The sum of the Pyro Valences in this mixture is -2.95 therefore, this mixture is oxidizer rich, and the addition of more titanium should yield an even more reactive formulation. If the valences had added up to zero, the mix would have been stoichiometric. 

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Earlier we noted that an acid-base titration may be used to analyze a mixture of acids or bases by titrating to more than one equivalence point. The concentration of each analyte is determined by accounting for its contribution to the volume of titrant needed to reach the equivalence points. 

ITie BET method is the most widely used procedure for determining the surface area of porous materials. In this chapter, BET results were obtained from single point measurements using a Micromeritics Flowsorb II 2300 surface area analyzer. A mixture of nitrogen in helium (30 70 mole percentage) was used. Although this simple method is not quantitative for the microporous materials studied in section 5, it still allows qualitative comparisons to be made. 

Sometimes it is important to know under what conditions a precipitate will form. For example, if we are analyzing a mixture of ions, we may want to precipitate only one type of ion to separate it from the mixture. In Section 9.5, we saw how to predict the direction in which a reaction will take place by comparing the values of J, the reaction quotient, and K, the equilibrium constant. Exactly the same techniques can be used to decide whether a precipitate is likely to form when two electrolyte solutions are mixed. In this case, the equilibrium constant is the solubility product, Ksp, and the reaction quotient is denoted Qsp. Precipitation occurs when Qsp is greater than Ksp (Fig. 11.17). 

Not only chiral separations have been achieved with Mi-stationary phases. It has also been demonstrated that the MIP could distinguish between ortho- and para-isomers of carbohydrate derivatives. For example, a polymer imprinted with o-aminophenyl tetraacetyl P-D-galactoside was used to analyze a mixture of p-and o-aminophenyl tetraacetyl P-D-galactoside. As expected, the imprinted ortho analyte eluted after the non-imprinted para component see Fig. 5. Although baseline separation was not obtained, a separation factor of a = 1.51 was observed [19]. 

Lord et al. analyzed a mixture of steroids by CEC-ESI/MS and interfaced externally tapered CEC columns in both sheathless and sheath-flow arrangement. Sensitivity was found 20-fold higher in the sheathless configuration. The same conclusion was drawn by Warriner et ah, who evaluated CEC-nanospray/MS vs. CEC-microspray/MS with an ion trap using five corticosteroids. Cahours et al. used CEC-ESI/MS for a drug metabolism study and obtained a simultaneous baseline separation of flunitrazepam and its major metabolites. For CEC-ESI/MS coupling, the commercially available packed-CEC column was connected... 

Figure 8 (1., 6) shows the fractionation obtained by analyzing a mixture of polystyrene, poly(styrene co-n-butyl methacrylate) and poly(n-butyl methacrylate) with various n-heptane concentrations. 

It is seen from f igure (3) that there is a very wide range of analysis times extending from just over ten days, which was required to analyze a mixture... 

Chromatography is a well-known analytical method, but is also a validated industrial purification tool. However, the preparahve or produchon approach is very different from the analytical one. In analyhcal chromatography, the focus is on analyzing a mixture in order to separate the peaks of each component. The injected amount is small and peak resolution tends to be maximized. Column size is generally small in order to minimize analyhcal costs. An example of an analytical chromatogram is presented in Figure 12.1. 

To analyze a mixture of two compounds, it is necessary to measure absorbance at two wavelengths and to know e at each wavelength for each compound. Similarly, a mixture of n components can be analyzed by making n absorbance measurements at n wavelengths. 

Acid Hydrolysis. Lactose is resistant to acid hydrolysis compared to other disaccharides such as sucrose. In fact, organic acids, such as citric acid, that easily hydrolyze sucrose are unable to hydrolyze lactose under the same conditions. This is useful in analyzing a mixture of these two sugars, because the quantity of sucrose can be measured by the extent of these changes in the optical rotation of reducing power as a result of mild acid hydrolysis. The speed of hydrolysis of lactose varies with time, temperature, and concentration of the reactant, as shown in Table 6.8. 

Taylor et al. [39,56] analyzed a mixture of corticosteroids in extracts of equine urine and plasma. Gradient elution was used to facilitate trace enrichment at the head of the column. Huber et al. [36] presented another illustration for the use of capillary electrochromatography with gradient elution. Five steroid hormones were separated by using a capillary column packed with 6-pm Zorbax ODS stationary phase. 

To determine the composition of a peptide, one hydrolyzes the peptide (in acidic solution, since alkali causes racemization) and determines the amount of each amino acid thus formed. One of the best ways of analyzing a mixture of amino acids is to separate the mixture into its components by chromatography— sometimes, after conversion into the methyl esters (Why ), by gas chromatography. 

Hadj-Mahammed et al. analyzed a mixture of flavone, 5-methoxyflavone, and tangeretin by supercritical CO2 SFC on capillary columns with two types of detectors flame ionization (FID) and FT-IR. Peafe identification was achieved with the help of the FT-IR fingerprint of each compound. However, the separation was satisfactory only by the use of supercritical C02g density programs, without the use of a phase modifier. The separations were accomplished using a Carlo Erbaa SFC system equipped with a Model SFC 300 pump and Model SFC 3000 oven. The fused silica capillary column were BPl (12 mxO.l mm I.D. 0.1-pm film of di- methylpolysiloxane) and DB5 (15 mxO.l mm TD. 0.4-pm film of 94% dimethyl-, 5% diphenyl-, and 1% vinylpolysiloxane). The two supercritical CO2 density programs used in this work were PI [from 0.127 g/mIi->... 

One way to analyze a mixture of ions in solution is to separate the mixture into its components by exploiting the differences in the solubilities of compounds containing the ions. To separate silver ions from lead ions, for example, a search is made for compounds of these elements that (1) have a common anion and (2) have widely different solubilities. The chlorides AgCl and PbCb are two such compounds, for which the solubility equilibria are... 

How could you analyze a mixture of HCl and H3PO4 A mixture of Na3P04 and Na2HP04 See Figure 15-4, curve A. 

Use stoichiometry principles to analyze a mixture or to find the empirical formula of an unknown compound (Section 4.6). 

We can simplify Eq. (14-1) considerably for special cases. As it stands, it applies only to a pure substance. But suppose that we wish to analyze a mixture of two phases, a and p. Then we can concentrate on a particular line of the a phase and rewrite Eq. (14-1) in terms of that phase alone. / now becomes / the intensity of the selected line of the a phase, and the right side of the equation must be multiplied by c the volume fraction of a in the mixture, to allow for the fact that the diffracting volume of a in the mixture is less than it would be if the specimen were pure a. Finally, we must substitute p, for p, where p is the linear absorption... 

We now turn to the case of noise spectroscopy and in particular consider the important issue of the number of sensors needed to analyze a mixture of different chemical species. It is first assumed that oidy one sensor is present. If the power density spectrum of the resistance fluctuations in this sensor has K different frequency ranges, in which the dependence of the response on the concentration of the chemical species is different from the response in the other ranges, one can write... 

Cooks and co-workers [241] analyzed a mixture of volatile phenolics obtained from Dolichothele uberiformis by Soxhlet extraction. Ionization method was with El (or Cl). 

Chemists often analyze mixtures to determine their compositions. Their analytical procedures may include gas chromatography, mass spectrometry, or infrared spectroscopy. In this Chem-Lab, you wiU use a double-displacement reaction between strontium chloride and sodium sulfate to analyze a mixture of sodium sulfate and sodium chloride. 

Theoretical Yield and Actual Yield Determining Mass Percents Determining Ghemical Formulas MiniLab 12.2 Bagging the Gas ChemLab Analyzing a Mixture... 

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