Useful Units

We need to convert the standard pressure of 1 atm to other units. Imagine freezing metallic mercury and machining 76 nice shiny cubes exactly (1 cm) x (1 cm) x (1 cm) = 1 cm with the density of 13.596 g/cm and then stacking 76 them in a column to evaluate the force on a 1 cm area to yield a pressure as (pressure = force/area). 

This is approximate to help visualize the unit but when more accurate values are used the standard conversion is 

It will be convenient for some applications to use cgs units so we need to remember what a dyne is. 

So we have several alternative values for R in different units  

One of the most common errors students make is to use the incorrect value ofR because they forget to check the units. We could standardized the book on SI units, but in the real world there is a lot of equipment out there using all kinds of units and you will be better prepared if you learn to cope with different unit systems including the SI units. 

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The viscosity is expressed in Pa s. The commonly used unit is mPa-s, formerly called centipoise, cP. 

The kinematic viscosity is defined as the ratio between the absolute viscosity and the density. It is expressed in m /s. The most commonly used unit is mm /s formerly called centistoke, cSt. 

Reservoir fluids are broadly cafegorised using those properties which are easy to measure in the field, namely oil and gas gravity, and the producing gasioil ratio (GOR) which is the volumetric ratio of the gas produced at standard condition of femperature and pressure (STP) fo fhe oil produced at STP. The commonly used units are shown in the following table. 

N. is Avogadro s constant. The most commonly used unit then is cm s sometimes inconsistently written — 1... 

Because of the restricted availability of computational resources, some force fields use United Atom types. This type of force field represents implicitly all hydrogens associated with a methyl, methylene, or methine group. The van der Waals parameters for united atom carbons reflect the increased size because of the implicit (included) hydrogens. 

Caution If you are new to computational chemistry, do not use United Atoms for AMBER calculations. This HyperChem option is available for researchers who want to alter atom types and parameters for this force field. 

TABLE 1-4 Conversion Foelors U.S. Customary and Commonly Used Units to SI Units... 

Quantity used unit SI unit SI unit obtain SI unit... 

Quantity Customary or commonly used unit SI unit Alternate SI unit Conversion factor multiply customary unit by factor to obtain SI unit ... 

Large databases for the solubility parameter exist, most notably Barton s Handbook of Solubility Parameters and Other Cohesive Parameters [112], A small listing of values is given in Table 4. The units used are those of (J/cm ) / = (MPa) /, although the older literature uses units of (cal/cm ). The units are related by ... 

I have used units likely to be most familiar to the majority of my readers. Although I welcome the increasing use of SI units, many people still use imperial units—they are more familiar with a 1-in. pipe that a 25-mm pipe-... 

Converting a measurement from one unit to anotlier can conveniently be accomplished by using unit conversion factors, tliese factors are obtained from tlie simple equation that relates tlie two units numerically. The following is an example of a unit conversion factor... 

Density is defined as the mass of unit volume of a material at a specific temperature. A more useful unit used by the petroleum industry is... 

But that is not all. For dilute solutions, the solvent concentration is high (55 mol kg ) for pure water, and does not vary significantly unless the solute is fairly concentrated. It is therefore common practice and fully justified to use unit mole fraction as the standard state for the solvent. The standard state of a close up pure solid in an electrochemical reaction is similarly treated as unit mole fraction (sometimes referred to as the pure component) this includes metals, solid oxides etc. 

Nuclide masses are ordinarily tabulated using units of grams per mole. Therefore, to compute HE, it is useful to rewrite Equation with energy in units of kilojoules per mole and the change in mass in grams per mole ... 

Calcination is a widely used unit operation in process metallurgy, and the compound represented as solid 1 is usually a carbonate and solid 2, an oxide. The decomposition of hydroxides, besides being termed as drying as indicated in the previous section, is also called calcination. 

MD simulations of melts of C44H90, based on classic techniques in continuous space, have been reported recently using united atom [146] and fully atomistic [145] representations of the chain. Time in the conventional MD simulations is expressed in seconds, whereas time in the simulation of the coarse-grained chains on the 2nnd lattice is expressed in MC steps. Nevertheless, a few comparisons are possible via the longest relaxation time, rr, deduced from the decorrelation of the end-to-end vector ... 

To model the amidation and cyclization reactions, an internal standard was weighed into the feed, and the feed placed on a balance for continuous weighing during the reaction. The HPLC system was calibrated using units of mol/kg, so that density effects could be neglected. A series of experiments... 

Commonly used units for viscosity include the following ... 

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