Gas constant units

The basic thermophysical properties of selected gases at 1 atm is shown in Table 1.6. Gas constant units... 

Arrhenius activation energy and gas constant units differ by a factor of 1000.)... 

R is the gas constant per mole, while K is the temperature unit Kelvin). The dashed lines represent metastable extensions of the stable phases beyond the transition temperatures. 

In this expression, cos 0 is the average value of cos 0 the weighting factor used to evaluate the average is given by the Boltzmann factor exp(-V /RT), where R is the gas constant in the units of and T is in degrees Kelvin. Note that the correction factor introduced by these considerations reduces to unity if... 

Invert Eq. (4.49) and substitute. The ratio of gas constants is convenient for unit conversion ... 

So far, so good. The situation is really no different, say, than the ideal gas law, in which the gas constant is numerically different and has different units depending on the units chosen for p and V, The unit change in Example 10.1 is analogous to changing the gas constant from liter-atmospheres to calories it is apparent that one system is physically more meaningful than another in specific problems. Several considerations interfere with this straightforward parallel, however, and cause confusion ... 

M refer to the density and molecular weight of /, and R is the gas constant. For simplicity, we assume each component to be monodisperse mote complex expressions result when polydispersity is considered (6). This model also assumes the heat of mixing pet unit volume follows a van Laar-type relation where B is... 

Tj is the surface excess (Davies and Rideal, Jnteifacial Phenomena, 2d ed.. Academic, New York, 1963). For most purposes, it is sufficient to view Vj as the concentration of adsorbed component i at the surface in units of, say (g mol)/cm . R is the gas constant, T is the absolute temperature, Y is the surface tension, and a is the activity of component i. The minus sign shows that material which concentrates at the surface generally lowers the surface tension, and vice versa. This can sometimes be a guide in determining preliminarily what materials can be separated. 

Here R is the Universal Gas Constant (8.31 Jmol K ) and Q is called the Activation Energy for Creep - it has units of Jmol . Note that the creep rate increases exponentially with temperature (Fig. 17.6, inset). An increase in temperature of 20 C can double the creep rate. 

Ideal gas obeys the equation of state PV = MRT or P/p = MRT, where P denotes the pressure, V the volume, p the density, M the mass, T the temperature of the gas, and R the gas constant per unit mass independent of pressure and temperature. In most cases the ideal gas laws are sufficient to describe the flow within 5% of actual conditions. When the perfect gas laws do not apply, the gas compressibility factor Z can be introduced ... 

The term R is the gas constant which has the following values in different units ... 

The Arrhenius equation relates the rate constant k of an elementary reaction to the absolute temperature T R is the gas constant. The parameter is the activation energy, with dimensions of energy per mole, and A is the preexponential factor, which has the units of k. If A is a first-order rate constant, A has the units seconds, so it is sometimes called the frequency factor. 

R = gas constant, depends on units of pressure, volume, and temperature... 

T = absolute temperatures, °R (Rankine) = °F + 460 R = universal gas constant = 10.729 for units noted here Z = compressibility factor N = number of lb-moles of gas... 

The y-coordinale in Figure 9.2b is In P, and the x-coordinate is 1/T. The slope, which is a negative quantity, turns out to be — AHvap/R, where AHnv is the molar heat of vaporization and R is the gas constant, in the proper units. Hence the equation of the straight line in Figure 9.2b is... 

When used as a standard electrode, the hydrogen electrode operates in a solution containing hydrogen ions at constant (unit) activity based usually on hydrochloric acid, and the hydrogen gas must be at 1 atmosphere pressure the effect of change in gas pressure is discussed in Ref. 28. 

In this book, we will express our thermodynamic quantities in SI units as much as possible. Thus, length will be expressed in meters (m), mass in kilograms (kg), time in seconds (s), temperature in Kelvins (K), electric current in amperes (A), amount in moles (mol), and luminous intensity in candella (cd). Related units are cubic meters (m3) for volume, Pascals (Pa) for pressure. Joules (J) for energy, and Newtons (N) for force. The gas constant R in SI units has the value of 8.314510 J K l - mol-1, and this is the value we will use almost exclusively in our calculations. 

The slope of the Arrhenius plot has units (temperature) 1 but activation energies are usually expressed as an energy (kJ mol 1), since the measured slope is divided by the gas constant. There is a difficulty, however, in assigning a meaning to the term mole in solid state reactions. In certain reversible reactions, the enthalpy (AH) = E, since E for the reverse reaction is small or approaching zero. Therefore, if an independently measured AH value is available (from DSC or DTA data), and is referred to a mole of reactant, an estimation of the mole of activated complex can be made. 

If H is the enthalpy of the humid gas per unit mass of dry gas, Ha the enthalpy of the dry gas per unit mass, Hw the enthalpy of the vapour per unit mass, Ca the specific heat of the gas at constant pressure, Cw the specific heat of the vapour at constant pressure. 0 the temperature of the humid gas, 0a the reference temperature, X the latent heat of vaporisation of ihe liquid at 6 0 and the humidity of the gas. 

The constant R is called the gas constant and has the same value for all gases because R is independent of the identity of the gas, we say that it is a universal constant. The value of the gas constant can be found by measuring P, V, n, and T and substituting their values into R = PV/nT. When we use SI units (pressure in pascals, volume in meters cubed, temperature in kelvins, and amount in moles),... 

PjPk = active intermediate of any length with comonomer j and k as penultimate and ultimate units, respectively R = rate function for total monomer conversion (rate of polymerization) or any rate function with appropriate subscript Rp = rate function defined in Table I Rg = gas constant... 

---