Acidity, expression

In the discussion of the relative acidity of carboxylic acids in Chapter 1, the thermodynamic acidity, expressed as the acid dissociation constant, was taken as the measure of acidity. It is straightforward to determine dissociation constants of such adds in aqueous solution by measurement of the titration curve with a pH-sensitive electrode (pH meter). Determination of the acidity of carbon acids is more difficult. Because most are very weak acids, very strong bases are required to cause deprotonation. Water and alcohols are far more acidic than most hydrocarbons and are unsuitable solvents for generation of hydrocarbon anions. Any strong base will deprotonate the solvent rather than the hydrocarbon. For synthetic purposes, aprotic solvents such as ether, tetrahydrofuran (THF), and dimethoxyethane (DME) are used, but for equilibrium measurements solvents that promote dissociation of ion pairs and ion clusters are preferred. Weakly acidic solvents such as DMSO and cyclohexylamine are used in the preparation of strongly basic carbanions. The high polarity and cation-solvating ability of DMSO facilitate dissociation... 

Free mineral acidity H2SO4, HCl, and other acids, expressed as CaCOj. Causes rapid corrosion and deterioration of surfaces. 

Fish and Shellfish. Sardines in oil and also in tomato sauce and mustard sauce are packed commercially in enameled aluminum cans. However, tomato and mustard sauces are corrosive products that can attack metal containers. Sardines prepared in these sauces should not exceed 3.0% total acidity, expressed as acetic acid. Otherwise, the presently used interior can enamels will not protect the food sufficiently to prevent chemical reactions with the metal. 

C13-0087. The smallest proteins contain about 50 amino acids. How many different proteins containing 50 amino acids can be formed from the 20 common amino acids Express your answer in power of 10 notation. 

In order to arrive at values of the virtually intrinsic acidity, i.e., an acidity expression independent of the solvent used (Tremillon12 called it the absolute acidity), Schwarzenbach13 used the normal acidity potential as an expression for the potential of a standard Pt hydrogen electrode (1 atm H2), immersed in a solution of the acid and its conjugate base in equal activities analogously to eqn. 2.39 for a redox system and assuming n = 1 for the transfer of one proton, he wrote for the acidity potential... 

For protonation-dehydration processes, such as trityl cation formation from triphenylcarbinols, equation (24), the water activity has to be included if the formulation of the activity coefficient ratio term is to be the same as that in equation (7), which it should be if linearity in X is to be expected see equation (25). The excess acidity expression in this case becomes equation (26) this is a slightly different formulation from that used previously for these processes,36 the one given here being more rigorous. Molarity-based water activities must be used, or else the standard states for all the species in equation (26) will not be the same, see above. For consistency this means that all values of p/fR listed in the literature will have to have 1.743 added to them, since at present the custom... 

Wilson ME, Price RH, Handa RJ (1998) Estrogen receptor-/ messenger ribonucleic acid expression in the pituitary gland. Endocrinology 139 5151-5156... 

An official gas chromatographic method [29] is available from the determination of volatile fatty acids in sewage sludge. This method is based on gas liquid chromatographic estimation with a flame ionization detector, and is applicable up to 2000mg total volatile fatty acids per litre, while the concentrations of individual fatty acids can also be determined. Where this method is not practicable an empirical method based on the spectrophotometric determination of ferric hydroxamates can be used, giving a value for total fatty acids expressed as acetic acid. For control purposes a rapid test is described in which the volatile fatty acids are determined by electrometric titrimetry on the neutralized sludge obtained from the determination of alkalinity. 

The threshold limit for aromatic aminosulfonic acids, expressed as aniline sulfonic acid, must be below 500 ppm. 

Base number the quantity of acid, expressed in milligrams of potassium hydroxide per gram of sample, that is required to titrated a sample to a specified endpoint. 

A 10.0 g sample of pure acetic acid, CH3CO2H, is completely burned. The heat released warms 2.00 L of water from 22.3°C to 39.6°C. Assuming that no heat was lost to the calorimeter, what is the enthalpy change of the complete combustion of acetic acid Express your answer in units of kj/g and kj/mol. 

The percent dissociation of a weak acid is the fraction of acid molecules that dissociate compared with the initial concentration of the acid, expressed as a percent. (Some chemists refer to percent dissociation as percent of dissociation.] The percent dissociation depends on the value of Ka for the acid, as well as the initial concentration of the weak acid. The following Sample Problems show how to solve problems that involve percent dissociation. 

Sanno, N., Jin, L., Qian, X., Osamura, R. Y., Scheithauer, B. W., Kovacs, K., and Lloyd, R. V. (1997) Gonadotropin-releasing hormone and gonadotropin-releasing hormone receptor messenger ribonucleic acids expression in nontumorous and neoplastic pituitaries. J. Clin. Endocrinol. Metab. 82, 1974-1982. 

N concentration of nucleic acids (in mg/ml) P concentration of protein (in mg/ml) d optical path (in cm) T [nucleic acid expressed as part of the total (protein -1- nucleic acid)] and factor F from Table 1.10. 

So you have 1.6 mol of base for every 1 mol of acid. Expressing the amount of base as a fraction of the total amount of acid and base therefore gives you... 

Cetkovic-Cvrlje, M., Sandler, S., and Eizirik, D. L. (1993). Nicotinamide and dexa-methasone inhibit interleukin-1-induced nitric oxide production by RINmSF cells without decreasing messenger ribonucleic acid expression for nitric oxide synthase. Endocrinology (Baltimore) 133, 1739-1743. 

Following are some data from an Australian soil trial in which a sample of soil was analyzed three times by each of 10 laboratories for TP A (total peroxide acidity expressed as moles per tonne). The results are given in spreadsheet 2.3. The sample variance is calculated as the square of the sample standard deviation, and the Cochran statistic is calculated from equation 2.20. 

Figure 9.5 Changes in titratable acidity (O), lactic acid ( ) and lactose ( ) on heating homogenized milk in sealed cans at 116°C. Titratable acidity expressed as mg lactic acid/100 g...

The isothermal solubility curve of mixtures of potassium sulphate and sulphuric acid expresses the composition of the soln. at 25° in equilibrium with the solid phase or phases, when the mol. ratio of K2SO4 and SO3 per 1000 grms. of soln. are plotted as co-ordinates. The ranges of stability in the ternary system K20—S03—H20, are diagrammed in Fig. 51, where the conditions have been studied in the vicinity of the SOs-apex, as far as the formation of KHS207, hut not as far as the well-known potassium pyrosulphate. The meaning of the diagram... 

Cultured buttermilk is manufactured by fermenting whole milk, reconstituted nonfat dry milk, partly skimmed milk, or skim milk with lactic acid bacteria. Most commercial cultured buttermilk is made from skim milk. Mixed strains of lactic streptococci are used to produce lactic acid and leuconostocs for development of the characteristic diacetyl flavor and aroma. Buttermilk is similar to skim milk in composition, except that it contains about 0.9% total acid expressed as lactic acid. The percentage of lactose normally found in skim milk is reduced in proportion to the percentage of lactic acid in the buttermilk. According to White (1978), the fat content of buttermilk usually varies from 1 to 1.8%, sometimes in the form of small flakes or granules to simulate churned buttermilk, the by-product of butter churning. Usually 0.1% salt is added. 

Gain in body weight divided by weight of protein consumed The content of the most limiting amino acid expressed as a percentage of the content of the same amino acid in egg protein... 

Coefficient d echange (Fr) (Exchange Coefficient). In order to det if a NC is sufficiently stabilized, Vieille detd titrimetrically the amt of acid (expressed as mg of H2S04) removed from each lOOg of NC in each hour of washing with w or dil alkali solns. He found that as soon as the coeficient drops to ca 5 (from original of about 150), the stabilization may be considered as completed. This method was improved by using pH meters for detn of acidity... 

Total acidity. This acidity, expressed as tartaric acid, varies from 4-5 to 15-X6 grams per litre. Wines rich in alcohol are relatively less acid than those of low alcohol content, owing to precipitation of the potassium bitartrate by the alcohol. Further, the total acidity of a wine diminishes as the wine ages, in consequence of precipitation Of this salt and also Of the tannin and likewise of decomposition of the malic acid into lactic acid Of one-half the equivalent acidity. On the other hand, the total acidity may be increased indirectly as a result of certain diseases of the wine which increase the volatile acidity. 

According to J. Dalton, 100 vols. of nitric add of sp. gr. 1-3 absorb 20 vols. of nitric oxide. He added that the amount of nitric oxide absorbed is proportional to the cone, of the acid, HNO3 very dil. acid absorbs scarcely any more nitric oxide than does pure water. A. V. Schaposchnikoff measured the coefi. of absorption of nitric oxide by nitric acid expressed in litres of gas per litre of acid of different cone., N, at 25° ... 

Amounts of D-, l-, and total glutamic acid expressed as moles/100 gram-... 

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