Gram-molecule

The mol fraction of any constituent in a mixture is defined as the number of mols, or gram molecules, of that constituent divided by the total number of mols, or gram molecules, in the mixture. 

In the calculation of yields, the term mol is usually employed. A mol (or mole or gram molecule) is equal to the molecular weight in grams. Hence the number of mols is equal to the weight of the substance in grams divided by the molecular weight. 

Another empirical equation due to Semenov relates the activation energy to the formation energy of the product molecule reaction A/f gg. For two gram-molecules of HI this is 600 kJ, and substituting in the equation... 

The transition from one phase to another is called phase-transition it takes place at a definite temperature (under a specified pressure) with the absorption of an amount of heat A for each gram-molecule, or mol, passing over. When the various phases of a system can exist side by side for an indefinite period they are said to be in equilibrium. 

From his equation Planck was able to calculate the number of atoms in a gram-molecule ... 

In aqueous solutions, concentrations are sometimes expressed in terms of normality (gram equivalents per liter), so that if C is concentration, then V = 103/C and a = 103 K/C. To calculate C, it is necessary to know the formula of the solute in solution. For example, a one molar solution of Fe2(S04)3 would contain 6 1CT3 equivalents cm-3. It is now clear as to why A is preferred. The derivation provided herein clearly brings out the fact that A is the measure of the electrolytic conductance of the ions which make up 1 g-equiv. of electrolyte of a particular concentration - thereby setting conductance measurements on a common basis. Sometimes the molar conductance am is preferred to the equivalent conductance this is the conductance of that volume of the electrolyte which contains one gram molecule (mole) of the ions taking part in the electrolysis and which is held between parallel electrodes 1 cm apart. 

The % yield is calculated with respect to the total number of gram-molecules of both monomers added 2. The intervals between the start of the isobutene polymerisation and the addition of the styrene were about 3 minutes, those between the addition of styrene and the addition of water about 5 minutes ... 

Figure 5.12. Electrode potential of Ag/Ag electrode as a function of Ag concentration. Molality is the concentration expressed as gram-molecules or gram-ions solute per liter (55 mol) of water. (From Ref. 5, with permission from Van No strand Reinhold.)...

Roy. SoG. A, Lxxxv. 557,1911), who employed a solution of nonylic acid. Their method of determining F was ingenious. A slow stream of air-bubbles was blown up through the solution, and the number and diameter of the bubbles was determined. Adsorption of solute occurred at the surface of each bubble, and the quantity so adsorbed was carried with the bubble into an upper part of the experimental vessel. Diffusion of solute back into the lower portion of the vessel was prevented by suitable baffles and the upper part gradually increased in concentration. If n was the number and r the radius of the bubbles, v the volume of the upper compartment of the vessel in c.c.s and Ac the concentration change in gram-molecules per square centimetre,... 

If in reaching the balance point a molecule from the surface layer does work per gram molecule, then the number of molecules reaching the balance point from the surface per second is... 

In this eq, the constants b and R are proportional to the mass taken, while a is proportional to the square of the mass. In discussion which follows, the values of the constants a b will be taken to refer to the same mass as is implied by the other variables, e.g. the use of V Sc R will imply one-gram molecules of the substance... 

Heat of Decomposition. The heat evolved or absorbed in a particular decomposition process. Thus the heat of decomposition of A B + C is usually different from A ->-B + D. However, A->-E+F B+C has the same net heat effect as A ->-B + C. The heat of decomposition is generally expressed in kg calories per gram molecule or in calories per gram... 

A large variety of reducing agents have been proposed for this reduction. However, zinc and sodium hydroxide offer the most common system, and lithium aluminum hydride merits consideration. The reduction of azoxy compounds with lithium aluminum hydride has value mainly in structural determinations. Its importance as a preparative procedure is limited normally such a reaction sequence would be a matter of putting the cart before the horse. The reduction of azines has potential value because of the accessibility of azines unfortunately, only under specialized circumstances has it been possible simply to add the required gram-molecule of hydrogen to the structure. Usua-ally, chlorine is added to an azine structure to produce dichloro azo compounds. An extension of the reaction permits the preparation of a,a -diacyl-oxyazoalkanes from azines. 

The azines represent another class of organic compounds which, in principle, should be reducible to azo compounds. The method is attractive since, with the availability of anhydrous hydrazine, azines are readily prepared from a wide variety of ketones and aldehydes. Evidently, introduction of 1 gram-molecule of hydrogen into an azine molecule has only recently been accomplished (see Section 6, Procedure 8) [73], Two preparations involving the 1,4-addition of chlorine to an azine system have been carried out and are illustrated here. 

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