Weight deposited

Measurements of cv at moderate temperatures were made by Joly in a steam calorimeter. The weight of water condensed from steam blown through a chamber containing a copper globe filled with gas was compared with the weight deposited on a similar but vacuous globe. 

GL 18] ]R 1] ]P 19a-d] High-molecular-weight deposits are assumed to form on the catalyst and can be removed by heating to 130 °C [60, 62], The activity loss is fast, but recoverable. In contrast, palladium loss, another cause of deactivation, is not as fast, but is irrecoverable. This loss decreases gradually in the course of processing, in some cases reaching near-constant behavior. 

Naphthenic and aromatic compounds oxidize to form high-molecular-weight deposits... 

Olefins participate in a variety of oxidation reactions which lead to the formation of carbonyl compounds, gums, and high-molecular-weight deposits... 

Fuel performance problems initiated by light are not common. However, fuel quality can be affected. The primary concern of light exposure is fuel color darkening and the possible formation of high-molecular-weight deposits due to free-radical-initiated polymerization of fuel components. 

For example, the decomposition of a hydroperoxide to generate an alkoxy free radical can result in the reaction of the alkoxy radical with an olefin. A carbon radical then forms. Olefin chain propagation and polymerization can follow to yield high-molecular-weight deposits. 

Lower Conductivity. The equivalent conductance of nonaqueous solutions a( infinite dilution is often comparable to that of aqueous systems, but it decreases with an increase in concentration more rapidly than the corresponding aqueous systems (the effect of the lower dielectric constant). Since the specific conductivity, K (that which determines the resistance between cathode and anode) is proportional to Ac, the equivalent conductance, the IR drop between the electrodes of a cell in which deposition from nonaqueous solutions is to lake place will be greater than that in aqueous solution (see Section 4.8.7). The electricity needed to deposit a given mass of metal is proportional to the total E between the electrodes, and this includes the IR between the electrodes, which is much greater in the nonaqueous than in the aqueous cases. Hence, nonaqueous deposition will be more costly in electricity (more kilowatt hours per unit of weight deposited) than a corresponding deposition in aqueous solution. The difference may be prohibitive. 

In this context, additional isobutane availabilities could be derived from n-butane isomerization, an operation which offers two variants, one of them induding the recyding of unconverted n-butane after separation. As a rule, isomerization takes place in the gas phase, around 150 to 200"C, under hydrogen pressure (13 to 15.10 Pa absolute), in the presence of a fixed catalyst bed of the reforming type, based on platinum (0.35 per cent weight) deposited on alumina promoted by traces of organic chlorides. Ooce-through... 

If the removable liner is divided into identical strips, dried and weighed, the weight deposited on each strip may be used to find the size distribution [71]. The constant k may be evaluated from curves given by Hauser and Lynn [72] or a nomograph developed by Saunders [73] may be used. 

Similarly, it is possible to study the affinity of an element for a support in a mixture of supports. The example shown in Figure 8.14 concerns a Pt-based catalyst (2.4% weight) deposited in a zeolite-alumina mixture containing 8% weight of zeolite. The zeolite is present in variable proportions depending on the area analysed. Since the Si/Al ratio of the zeolite is known, it is possible to calculate this proportion at each analysis point. 

The tar sands situated in Alberta consist of oil-bearing sandstones. Surface exposures occur in parts of the Athabasca deposit, but much of the deposit lies 100 m or more beneath the surface. Oil present in these Lower Cretaceous sandstone deposits is very viscous, thick, and partially oxidized so that it cannot be recovered by pumping alone. Hence, the term tar or bitumen describes this heavy oil fraction, which averages about 12% ranging up to as much as 18% of the deposit by weight. Deposits with less than 2-3% bitumen are excluded from the reserve data given in Table 17.4. 

The Knudsen effusion technique entails heating a small quantity of the material under study in a refractory container, in a high vacuum, see the front cover of this book. Vapour effuses, through a small pinhole in the lid, and sprays on to a cold surface, where it condenses. After several hours, the deposit is weighed. Vapour pressures, such as those in Table 8.1, may then be calculated from the pinhole size, the deposition time, the weight deposited, and other constant factors. If the pinhole is sufficiently small, then equilibrium conditions may be assumed to prevail inside the cell. 

It should be noted that the 0.2 wt% Y-MPS point does not fit the trend of the rest of the data.. We are confident that this is a real phenomenon. It is quite possible that for a low concentration of the silane (which produces low molecular weight deposit), silane-epoxy interdiffusion increases the W (resin)/W (water) ratio. Apparently, in... 

Catalyst. The catalyst was lOg of 0.5% platinum by weight, deposited on the surface of 1/8 inch in diameter y alumina pellets and obtained from Engelhard Ltd., Cinderford, England. 

When Hj represents the base of the centrifuge, then is the Stokes diameter of the fineparticles that will just have reached the base by time t. Let be the weight deposited on the base at time t then... 

The electrochemical equivalent of an element is the weight deposited or dissolved by the passage of 1 coulomb in an electrolytic process. By Faraday s laws (q.v.) it should equal the gram-equivalent weight divided by the Faraday constant (q.v.). Thus, the electrochemical equivalent of silver is 1.118 mg C and this multiplied by 96 490 (the Faraday constant) gives 107.88, the relative atomic mass of silver. 

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