Unknown liquids, list

For a solvent that is not listed, the procedure for estimating the M number is to determine the cut-off point for miscibility using a sequence of known solvents. A correction term of 15 is then either added or subtracted, whichever is appropriate. Solvents used in these tests should of course be pure. After the miscibility number is determined, an experiment should be run to verify the solubility of the two solvents. For example, if a liquid has borderline solubility in dimethyl sulfoxide (M = 9), the M number assigned is 24. On the other hand, if an unknown liquid was borderline soluble in p-xylene (M = 24) its M number is estimated to be 9. Reference 20 has a list of approximately 400 liquids and should be consulted by those who are interested. 

By the use of the techniques listed above it ought to be possible to determine the identity of an unknown liquid crystal from a display. 

The two mixed tellurium(IV) halides listed in Table 16.5 were prepared by the action of liquid Br2 on TeCl2 to give the yellow solid TeBr2Cl2, and by the action of I2 on TeBr2 in ether solution to give the red crystalline TeBr2l2 their structures are as yet unknown. 

For a given geometry of the set-up, the relevance list for this problem contains the power consumption, P, as the target quantity, the stirrer diameter, d, as the characteristic length and a number of physical properties of the liquid and the gas (the latter are marked with an apostrophe) Densities, p and p, kinematic viscosities, v and v, surface tension, a, and an unknown number of still unknown physical properties, S, which describe the coalescence behaviour of finely dispersed gas bubbles and by this, indirectly, their hold-up in the liquid. The process parameters are the stirrer speed, n, and the gas throughput, q, which can be adjusted independently, as... 

Shake in a small test tube ca 0,2g of ground unknown subst with ca 5ml of CC1. and allow to stand for 5mins. If the sample is completely sol it is usually TNT. Confirm its presence by treating the soln with one or more colori metric reagents listed in Charts A B. If the sample is only partially sol in CC14, remove the liquid portion and test it for TNT XVIX. Treatment with Acetone. If the subst is not completely sol in CC14 proceed as follows ... 

The superheated steam table. Table B.7, lists values for both liquid water and steam. If you wish to determine H for liquid water at a temperature T and pressure P that cannot easily be found in this table, you may calculate it in the following manner (1) look up U and V for sam-rated liquid at the specified temperature in Table B.5 (2) assume these values are independent of pressure, and calculate H P,T) = (7 + PV. Furthermore, if the pressure is not excessive (say, less than 10 bar) or if it is unknown, neglect the PV correction and use the saturated liquid enthalpy H(T) given in Table B.5. 

If we count the equations listed, we will find that there are 2n + 4 equations per stage. However, only 2 n + 3 of these equations are independent. These independent equations are generally taken to be the n component mass balance equations, the n equilibrium relations, the enthalpy balance, and two more equations. These two equations can be the two summation equations or the total mass balance and one of the summation equations (or an equivalent form). The 2n + 3 unknown variables determined by the equations are the n vapor mole fractions the n liquid mole fractions, the stage temperature 7 and the vapor and liquid flow rates LJ and Ly. Thus, for a column of 5 stages, we must solve s 2n + 3) equations. 

When the solution under investigation happens to be colored, the reference solution must be treated with a coloring agent possessing a color which resembles that of the unknown solution as closely as possible. It is evident that those indicators which are already completely transformed at the pH being investigated may be used for this purpose. For example, methyl orange can be added to a reference solution without hesitation to match the yellow-brown color of a liquid with a pH = 7. Sorensen has made a list of frequently used colorants. 

In this lesson, students use a third chemical liquid, red cabbage juice, to explore further the chemical properties unique to each unknown. Following the completion of this test, students analyze all the data they have collected over the past seven lessons and summarize what they now know about the physical and chemical properties of each of the five unknown solids. This is a good time for the class to add to the What We Think about Chemicals list from Lesson 1. 

Chemical analysis of hazardous substances in air, water, soil, sediment, or solid waste can best be performed by instrumental techniques involving gas chromatography (GC), high-performance liquid chromatography (HPLC), GC/mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR), and atomic absorption spectrophotometry (AA) (for the metals). GC techniques using a flame ionization detector (FID) or electron-capture detector (BCD) are widely used. Other detectors can be used for specific analyses. However, for unknown substances, identification by GC is extremely difficult. The number of pollutants listed by the U.S. Environmental Protection Agency (EPA) are only in the hundreds — in comparison with the thousands of harmful... 

From the measurables T, P, x , and jcP, five common phase equilibrium problems can be contrived, depending on which quantities are known and which are unknown. For example, the problem introduced in the previous paragraph involves P and x as known and requires us to solve (11.1.1) for T and xP. When phase a is liquid and phase 3 is vapor, this problem is called a bubble-T calculation, for we are to compute a point on the bubble curve of an isobaric Txy diagram. This along with the other four common problems are listed in Table 11.1. 

Cerium metal is discussed in ch. 4 and only a brief mention of its high pressure behavior will be made here (for references see the list in ch. 4). Cerium can exist at atmospheric pressure in the fee (y) or dhep (iS) form and undergoes an isostructural transition near 100 K to another fcc-form referred to as o-Ce. The y-a Ce transition occurs at 7 kbar at room temperature and this transition is accompanied by about 8% volume decrease. This is one of the most widely studied transitions as a function of pressure and temperature and is believed to involve a valence change from 3 towards a higher valence state (3.7 ). The y to a transition line terminates at a critical point the very first example in which a solid - solid transition was shown to exhibit a liquid-vapor-like critical point. A pressure-induced phase transition near 50 kbar, initially reported to be yet another isostructural transition has been shown to be from fee (a-Ce) to an orthorhombic phase with the a-U structure. Stager and Drickamer (1964) have reported a pronounced resistance anomaly near 120 kbar indicative of a phase transition, but the nature of this transition is unknown. The fusion behavior of Ce is again unique in that it exhibits a minimum. 

Using the structural information from the infrared spectrum and the boiling point of your unknown, identify this liquid from the list of compounds in the table. If you are working in a group, you will need to do this for all three compounds. In order to make use of the structural information determined from the infrared spectrum, you will need to know the structures of the compounds that have boiling points close to the value you experimentally determined. You may need to consult TheMerckIndex or the CRC Handbook of Chemistry and Physics. It may also be helpful to look up these compounds in the index of your lecture textbook. If there is more than one compound that fits the infrared spectrum and is within a few degrees of the experimental boiling point, you should list all of these in your laboratory report. 

Since p-toluidine a solid, it appeared to be e.xcluded from the list of ]x)ssibilities. However, tiie acetyl derivative of the unknown melted at 120° after one crystallization and at 146-7° after the seconil and subsequent purifications. This agreed with the value for the acetyl derivative of p-toluidine consequently a benzoyl derivative was prepared. It was found to melt at 157° and the mixed melting-point with known benzoyl-p-toluidine show ed an unchanged value. The difficult was easily explained in the light of these numerical data. The unknown, although of constant boiling-point, was a mixture of toluidines, the solid para compound being dissolved in the liquid ortho isomer. The acetyl derivative was a mixture, l)ut after several ciy stallizations from water the more soluble ortho compound was removed and pure acet-p-toluidine remained. 

The list of AMDIS identified compounds of the headspace analysis and liquid extractions are given in the following Tables 4.30 -4.32 with compound name, CAS numbers as well as the peak quality parameters retention time and the measured peak width and tailing information. The result of the mass spectrum library comparison is given in the most right columns. The Reverse fit column informs about the match quality in % of the spectrum pattern of the proposed library entry with the unknown spectrum (reverse search). 

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