Gram

Gibbs function (see Gibbs free energy, free energy) gram... 

For fuels it is quite usual to employ kilocalories per kilogram as a measure of calorific value while for foods the unit used is kilocalories per gram. This, however, is often abbreviated to Calories , so that a value for carbohydrates of 4-1 Calories per gram is 4100 calories per gram. 

The conductivity of a solution containing 1 gram equivalent of solute when measured between two large parallel electrodes at a distance of 1 cm apart is called the equivalent conductivity A. 

Erythromycin is active against gram-positive and certain gram-negative bacteria, also against Rickettsia and spirochaetes. It is used for patients who are allergic to or do not respond to treatment with penicillins or tetracyclines. 

It is a ratio. The molecular weight is equal to the sum of the atomic weights of the constituent nuclei. The molecular weight expressed in grams is known as the gram molecular weight. 

The maximum concentration atltainable under such conditions is termed the solubility of the substance at the specific temperature used in the experiment, since solubility generally increases with rising temperature. Solubility is usually expressed in grams per 100 g of solvent, or grams per 100 g of solution. Sometimes, for practical convenience, it may be expressed in grams per 100 ml of solvent or solution. 

Tetracyclines are broad-spectrum antibiotics. effective against Gram-positive and Gram-negative bacteria, also against Rickettsiae (typhus fever) and certain other organisms. 

This method follows the ASTM D 1159 and D 2710 procedures and the AFNOR M 07-017 standard. It exploits the capacity of the double olefinic bond to attach two bromine atoms by the addition reaction. Expressed as grams of fixed bromine per hundred grams of sample, the bromine number, BrN, enables the calculation of olefinic hydrocarbons to be made if the average molecular weight of a sufficiently narrow cut is known. 

MAV is expressed in mg of anhydride per gram of sample. It is still widely used to evaluate the quantity of conjugated, olefins in a fraction. This type of molecule is highly undesirable in a large number of end products because of its propensity to polymerize spontaneously and to form gums. 

The base products, TEL and TML, are liquids having boiling points of 205° and 110° respectively. The contents of additives used are usually expressed in grams of lead per liter of fuel in the past they have reached 0.85 g Pb/1. These concentrations are still found in some of the countries of Africa. Elsewhere, when part or all of the motor fuel pool contains lead, the concentrations are much smaller. Thus in Western Europe they no longer exceed 0.15 g Pb/1. 

More precisely, the rate of ozone formation depends closely on the chemical nature of the hydrocarbons present in the atmosphere. A reactivity scale has been proposed by Lowi and Carter (1990) and is largely utilized today in ozone prediction models. Thus the values indicated in Table 5.26 express the potential ozone formation as O3 formed per gram of organic material initially present. The most reactive compounds are light olefins, cycloparaffins, substituted aromatic hydrocarbons notably the xylenes, formaldehyde and acetaldehyde. Inversely, normal or substituted paraffins. 

Finally it is likely that attention will be focused on emissions of polynuclear aromatics (PNA) in diesel fuels. Currently the analytical techniques for these materials in exhaust systems are not very accurate and will need appreciable improvement. In conventional diesel fuels, emissions of PNA thought to be carcinogenic do not exceed however, a few micrograms per km, that is a car will have to be driven for several years and cover at least 100,000 km to emit one gram of benzopyrene for example These already very low levels can be divided by four if deeply hydrotreated diesel fuels are used. 

For that reason, we chose to build a "detection cartography" out of the 16 scalo-grams, by selecting one particularly pertinent scale for detection, and discarding all the... 

McBain reports the following microtome data for a phenol solution. A solution of 5 g of phenol in 1000 g of water was skimmed the area skimmed was 310 cm and a 3.2-g sample was obtained. An interferometer measurement showed a difference of 1.2 divisions between the bulk and the scooped-up solution, where one division corresponded to 2.1 X 10 g phenol per gram of water concentration difference. Also, for 0.05, 0.127, and 0.268M solutions of phenol at 20°C, the respective surface tensions were 67.7, 60.1, and 51.6 dyn/cm. Calculate the surface excess Fj from (a) the microtome data, (b) for the same concentration but using the surface tension data, and (c) for a horizontally oriented monolayer of phenol (making a reasonable assumption as to its cross-sectional area). 

It might be noted that only for particles smaller than about 1 /ig or of surface area greater than a few square meters per gram does the surface energy become significant. Only for very small particles does the edge energy become important, at least with the assumption of perfect cubes. 

The illustrative data presented in Table VII-3 indicate that the total surface energy may amount to a few tenths of a calorie per gram for particles on the order of 1 /xm in size. When the solid interface is destroyed, as by dissolving, the surface energy appears as an extra heat of solution, and with accurate calorimetry it is possible to measure the small difference between the heat of solution of coarse and of finely crystalline material. 

The excess heat of solution of sample A of finely divided sodium chloride is 18 cal/g, and that of sample B is 12 cal/g. The area is estimated by making a microscopic count of the number of particles in a known weight of sample, and it is found that sample A contains 22 times more particles per gram than does sample B. Are the specific surface energies the same for the two samples If not, calculate their ratio. 

The present discussion is restricted to an introductory demonstration of how, in principle, adsorption data may be employed to determine changes in the solid-gas interfacial free energy. A typical adsorption isotherm (of the physical adsorption type) is shown in Fig. X-1. In this figure, the amount adsorbed per gram of powdered quartz is plotted against P/F, where P is the pressure of the adsorbate vapor and P is the vapor pressure of the pure liquid adsorbate. 

The surface excess per square centimeter F is just n/E, where n is the moles adsorbed per gram and E is the specific surface area. By means of the Gibbs equation (111-80), one can write the relationship... 

The moles of a solute species adsorbed per gram of adsorbent nl can be expressed in terms of the mole fraction of the solute on the surface N and the moles of adsorption sites per gram as... 

Here, denotes the total number of moles associated with the adsorbed layer, and N and are the respective mole fractions in that layer and in solution at equilibrium. As before, it is assumed, for convenience, that mole numbers refer to that amount of system associated with one gram of adsorbent. Equation XI-24 may be written... 

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