Pressure in atmosphere

Kp = equilibrium constant at a given temperature X = fraction paraffin converted to mono-olefms P = reaction pressure in atmospheres... 

As an additional aid to readers seeking further information of a specific subject, references are included at the end of each chapter. Throughout the text, different units are used interchangeably as they are in the industry. However, in most cases temperatures are in degrees Celsius, pressures in atmospheres, and energy in kilo joules. 

Sulfur hexafluoride is a gas used as a long-term tamponade (plug) for a retinal hole to repair detached retinas in the eye. If 2.50 g of this compound is introduced into an evacuated 500.0-mL container at 83°C, what pressure in atmospheres is developed ... 

The equation just written is generally applicable to any system. The equilibrium constant may be the K referred to in our discussion of gaseous equilibrium (Chapter 12), or any of the solution equilibrium constants (Rw Ra, Rj, K, . . . ) discussed in subsequent chapters. Notice that AG° is the standard free energy change (gases at 1 atm, species in solution at 1M). That is why, in the expression for K, gases enter as their partial pressures in atmospheres and ions or molecules in solution as their molarities. 

Remember that gases enter Q as their partial pressures in atmospheres. Species in water solution enter as their molar concentrations. Pure liquids and solids do not appear in the expression for Q. For example,... 

Self-Test 4.3A The U.S. National Hurricane Center reported that the pressure in the eye of hurricane Katrina (2005) fell as low as 902 mbar. What is that pressure in atmospheres ... 

A television picture tube is a form of cathode-ray tube (Section 1.1) in which the beam of electrons is directed toward a screen that emits light where they strike it. Have you ever wondered what the pressure is inside the tube Estimate the pressure (in atmospheres), given that the volume of the tube is 5.0 L, its temperature is 23°C, and it contains 0.010 mg of nitrogen gas. 

Therefore, if we work in pascals and cubic meters, the work is obtained in joules. However, we might have expressed the pressure in atmospheres and the volume in liters. In this case, we may need to convert the answer (in liter-atmospheres) into joules. The conversion factor is obtained by noting that 1 L = 10 3 m3 and 1 atm = 101 325 Pa exactly therefore... 

Suppose the following data on the iodination of ethane have been obtained at 603 K using a recirculating gas-phase reactor that closely approximates a CSTR. The indicated concentrations are partial pressures in atmospheres and the mean residence time is in seconds. 

In this chapter, we work primarily with pressures in atmospheres or torr, but we use pressures in bars in later chapters when we work with standard chemical conditions. Example illustrates pressure measurement and unit... 

We must combine the reading from the manometer with the barometric pressure to find the pressure of the gas sample. The manometer displays the pressure difference in millimeters of mercury, so conversion factors are needed to express the pressure in atmospheres and bars. 

C05-0130. In 1990, carbon dioxide levels at the South Pole reached 351.5 parts per million by volume. (The 1958 reading was 314.6 ppm by volume.) Convert this reading to a partial pressure in atmospheres. At this level, how many CO2 molecules are there in 1.0 L of dry air at -45 °C ... 

C05-0145. Find the partial pressures in atmospheres of the eight most abundant atmospheric components listed in Table 5 at 25 °C, 50% relative humidity, and P = 765 torr. 

EXAMPLE 11.1. What is the pressure in atmospheres of a gas that supports a column of mercury to a height of 1090 mm ... 

In this equation, e is the actual potential and f° is the standard potential, n is the number of electrons involved, and Q is a ratio of concentration terms. Q is equal to the ratio of concentrations of products to concentrations of reactants, each raised to the power corresponding to the coefficient in the balanced chemical equation. Pure solids and liquids and the solvent water are not included in Q their effective concentrations are assumed to be 1. Gas pressures in atmospheres are used instead of concentrations. For a general reaction... 

In all three cases, Keq = Kp because only gases, solids, and liquids are present in the chemical equations. There are no factors for solids and liquids in K expressions, and gases appear as partial pressures in atmospheres. That makes ATeq the same as Kp for these... 

Solid carbon reacts with carbon dioxide gas to produce carbon monoxide. At 1,500°C, the reaction is found to be at equilibrium with a Kp value of 0.50 and a total pressure of 3.5 atm. What is the proper expression for the partial pressure (in atmospheres) of the carbon dioxide ... 

The value for R is 0.0821 L atm/K mol if the volume is expressed in liters, the pressure in atmospheres, and the temperature in Kelvin (naturally). You could calculate another ideal gas constant based upon different units of pressure and volume, but the simplest thing to do is to use the 0.0821 and convert the given volume to liters and the pressure to atm. (The temperature must be in Kelvin in any case.)... 

In this equation, u is the osmotic pressure in atmospheres, n is the number of moles of solute, R is the ideal gas constant (0.0821 Latm/K mol), T is the Kelvin temperature, V is the volume of the solution and i is the van t Hoff factor. If one knows the moles of solute and the volume in liters, n/V may be replaced by the molarity, M. It is possible to calculate the molar mass of a solute from osmotic pressure measurements. This is especially useful in the determination of the molar mass of large molecules such as proteins. 

For some steps the apparent activation energy is to be used in Eq. (10), and in others, the true activation energy. See text. (2) Where relevant, it is assumed that the symmetry number approximates unity it is also assumed that (Ijs) a 0.5, where s is the number of sites adjacent to a given site in a surface bimolecular reaction. (3) Both Cj, gas concentration in molecules cm", and P, gas pressure in atmospheres are used in this work. For an ideal gas, c, = 7.34 x 1q2i pij< 4 Except where otherwise noted, ft a 1. (5) An adsorption reaction is a Rideal-Eley reaction a surface reaction is a "Langrauir-Hinshelwood reaction. 

The first number in the parenthesis following the gas reactant is its pressure in atmospheres the second is the order with respect to that reactant. No order is recorded where the data were reported so that they can apply to only one step, or where none was given. 

Problem 15 What is the minimum pressure in atmospheres at which CO2 can occur as a liquid ... 

Of course, the equilibrium constant Km the latter equation does not have the same value as the ATin the equilibrium equation for ammonia. The numerical value of ATdepends on the particular reaction, the temperature, and the units used to describe concentration. For liquid solutions, the concentrations are usually expressed as molarity. For a mixture of gases, the concentration of each molecular species is commonly given either as molarity or as pressure in atmospheres. 

Temperature K Heat in kcal/100 grams Pressure in Atmospheres ... 

With pressure in atmospheres and all volumes in cubic centimeters, equation (14.3) can be rewritten in terms of the volume adsorbed at standard temperature (273.2 K) and pressure (1.0 atm)... 

---