Kilogram-moles gases

FIG. 14-78 Mass-transfer coefficients versus average gas velocity—HC1 absorption, wetted-wall column. To convert pound-moles per hour-square foot-atmosphere to kilogram-moles per second-square meter-atmosphere, multiply by 0.00136 to convert pounds per hour-square foot to kilograms per second-square meter, multiply by 0.00136 to convert feet to meters, multiply by 0.305 and to convert inches to millimeters, multiply by 25.4. [Dobratz et al., Chem. Eng. Prog,49, 611 (1953).]... 

Convert the natural gas flow rate to kilogram-moles per second. At the conditions of this problem, the ideal-gas law can be used. Thus, n = PV/RT, where n is number of moles, P is pressure, V is volume, R is the gas constant, and T is absolute temperature. 

One kilogram mole of N2 is in a horizontal cylinder at 1000 kPa and 20°C. A 6-cm piston of 2-kg mass seals the cylinder and is fixed by a pin. The pin is released and the N2 volume is doubled, at which time the piston is stopped again. What is the work done by the gas in this process ... 

The modelling of the gas accumulation process above has used kilograms as the unit. However, it is also possible to use the kilogram-mole (abbreviation kmol) as the unit of accumulation, which is often more convenient when a mixture of gases is being considered. 

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. 

Answer The first important thing to note is that the temperature is given in degrees Celsius and must be converted to Kelvin. The second important consideration is the units of the molar gas constant, R. The joule is a unit of energy that represents a Newton meter (N-m) in physics. The Newton is a unit of force equivalent to the amount of force required to accelerate a 1 kg mass at 1 m/s2. Why does this matter, you might ask Because it means that a joule can be described as a Newton meter, which is 1 kg m2/s2. Can you see the problem yet The mass unit associated with joules is the kilogram. Molar mass is usually expressed in grams/mole. To use the rms equation, you have to convert your mass units to kg. 

Here pe is the maximum pressure through the explosion (not to be confused with the much higher values for the detonation pressure pc.j at the C-J point), V is the volume of detonation gases (in 1 kg-1 or m3 kg-1), n is the number of moles of gas formed by the explosion per kilogram of explosive, R is the gas constant and T is the temperature of the explosion. The specific energy also has the units J kg-1. Consequently, the brisance can be given using the units kg s-3. 

Various units could be used for the solubilities, but the values given in the next section, the solubilities of both the acid gas components and the NaCl must be in molality (moles of salt per kilogram of solute). 

Water has an activity of 1 when Nw (see Eq. 2.8) is 1. The concentration of water on a molality basis (number of moles of a substance per kilogram of water for aqueous solutions) is then 1/(0.018016 kg mol-1) or 55.5 molal (m). The accepted convention for a solute, on the other hand, is that aj is 1 when yfj equals 1 m. For example, if yj equals 1, a solution with a 1 -m concentration of solute j has an activity of 1 m for that solute. Thus the standard state for an ideal solute is when its concentration is 1 m, in which case RT In a - is zero.2 A special convention is used for the standard state of a gas such as CO2 or O2 in an aqueous solution—namely, the activity is 1 when the solution is in equilibrium with a gas phase containing that gas at a pressure of 1 atm. (At other pressures, the activity is proportional to the partial pressure of that gas in the gas phase.)... 

In this expression m represents the mass in kilograms of a single gas particle. When Na, the number of particles in a mole, is multiplied by m, the product is the mass of a mole of gas particles in kilograms. We will call this quantity M. Substituting M for NAm in the equation for wrms, we obtain... 

A gas stream that contains 1.50 mole% CO2 flows through a pipeline. Twenty (20.0) kilograms of CO2 per minute is injected into the line. A sample of the gas is drawn from a point in the line 150 meters downstream of the injection point and found to contain 2.3 mole% CO2. 

Whether the adsorption isotherm has been determined experimentally or theoretically from molecular simulation, the data points must be fitted with analytical equations for interpolation, extrapolation, and for the calculation of thermodynamic properties by numerical integration or differentiation. The adsorption isotherm for a pure gas is the relation between the specific amount adsorbed n (moles of gas per kilogram of solid) and P, the external pressure in the gas phase. For now, the discussion is restricted to adsorption of a pure gas mixtures will be discussed later. A typical set of adsorption isotherms is shown in Figure 1. Most supercritical isotherms, including these, may be fit accurately by a modified virial equation. ... 

These questions and their answers will suggest suitable bases. Sometimes, when a number of bases seem appropriate, you may find it is best to use a unit basis of 1 or 100 of something, as, for example, kilograms, hours, moles, cubic feet. For liquids and solids when a weight analysis is used, a convenient basis is often 1 or 100 lb or kg similarly, 1 or 100 moles is often a good choice for a gas. The reason for these choices is that the fraction or percent automatically equals the number of pounds, kilograms, or moles, respectively, and one step in the calculations is saved. 

The molar heat capacity of a diatomic molecule is 29.1 J/K mol. Assuming the atmosphere contains only nitrogen gas and there is no heat loss, calculate the total heat intake (in kilojoules) if the atmosphere warms up by 3°C during the next 50 years. Given that there are 1.8 X 10 ° moles of diatomic molecules present, how many kilograms of ice (at the North and South Poles) will this quantity of heat melt at 0°C (The molar heat of fusion of ice is 6.01 kJ/mol.)... 

If mass is measured in kilograms or grams, constant in Eq. (1.4) differs from gas to gas. But when the concept of the mole as a mass unit is used, k, can be replaced by the universal gas constant R, which, by Avogadro s law, is the same for all gases. The numerical value of R depends only on the units chosen for energy, temperature, and mass. Then Eq. (1.4) is written... 

---