Vapor pressure of liquids

Fig. 33. Vapor pressure of liquid chlorine as a function of temperature (78).

TABLE 2-4 Vapor Pressure of Liquid Water from -16 to 0"C ... 

P,. = Vapor pressure of liquid at body inlet temperature, psia... 

Storage Vessels Vapor pressure of liquid at maximum ambient temperature plus 30° F. (usually 110° to 140° F.)... 

APPROX. VAPOR PRESSURE OF LIQUID-EXHAUST STEAM-------------------... 

Pj, = Brake horsepower at shutoff or no flow P[d = Differential pressure between absolute pressures at outlet and inlet to pump, psi P,p = Vapor pressure of liquid at pumping temperature, psia... 

In this case, Ptot is the measured pressure. The partial pressure of water vapor, Ph2o, is equal to the vapor pressure of liquid water. It has a fixed value at a given temperature (see Appendix 1). The partial pressure of hydrogen, PH2, can be calculated by subtraction. The number of moles of hydrogen in the wet gas, h2, can then be determined using the ideal gas law. 

Another expression that does a reasonably good job of representing vapor pressures of liquids, if the temperature range is not too great, is the Antoine equation ... 

E8.5 The vapor pressure of liquid helium can be expressed by the equation... 

Br(g) from the thermodynamic data provided in Appendix 2A. (b) What is the vapor pressure of liquid bromine (c) What is the partial pressure of Br(g) above the liquid in a bottle of bromine at 25°C (d) A student wishes to add 0.0100 mol Br2 to a reaction and will do so by filling an evacuated flask with Br2 vapor from a reservoir that contains only bromine liquid in equilibrium with its vapor. The flask will be sealed and then transferred to the reaction vessel. What volume container should the student use to deliver 0.010 mol Br2(g) at 25°C ... 

A fundamental property of a substance is the tendency for its atoms or molecules to spread into the surrounding space. A consequence of this property is the observed vapor pressure of liquids and solids. In order to understand the effects of the formation of a solution on this property, reference may be drawn to a solution consisting of two substances, A and B, with A being the solvent and B the solute. If the vapor pressure, PA, of the solvent over the solution is considered, it is clear that it must be proportional to the amount of A present in the solution. Thus,... 

Figure 5.19.2 A graph of the vapor pressure of liquid water as a function of temperature (on the left), and a graph of the natural logarithm of the vapor pressure of water as a function of the reciprocal of temperature.

Liquid ammonia is stored in a tank at 24°C and a pressure of 1.4 X 106 Pa. A pipe of diameter 0.0945 m breaks off a short distance from the vessel (the tank), allowing the flashing ammonia to escape. The saturation vapor pressure of liquid ammonia at this temperature is 0.968 X 106 Pa, and its density is 603 kg/m3. Determine the mass flow rate through the leak. Equilibrium flashing conditions can be assumed. 

The temperature is 80°F and the ambient pressure is 1 atm. Make sure you clearly state any assumptions. The vapor pressure of liquid butane at 80°F is 40 psia, and the specific gravity of liquid butane at 80°F is 0.571. 

The first example was formulated by Stoecker to illustrate the steepest descent (gradient) direct search method. It is proposed to attach a vapor recondensation refrigeration system to lower the temperature, and consequently vapor pressure, of liquid ammonia stored in a steel pressure vessel, for this would permit thinner vessel walls. The tank cost saving must be traded off against the refrigeration and thermal insulation cost to find the temperature and insulation thickness minimizing the total annual cost. Stoecker showed the total cost to be the sum of insulation cost i = 400jc° 9 (x is the insulation thickness, in.), the vessel cost v = 1000 + 22(p — 14.7)1-2 (p is the absolute pressure, psia), and the recondensation cost r = 144(80 — t)/x (t is the temperature, °F). The pressure is related to the temperature by... 

When the functional form of the correlation is suggested by theory, there is a great deal more confidence that the correlation can be extrapolated into regions of P that have no experimental data, and can be used for other families of compounds other than the training set S. Examples of theory-suggested functional forms include the van der Waals equation of state for gases, the Langmuir isotherm for adsorption and catalysis, and the Clausius-Clapeyron equation for the vapor pressure of liquids. 

H(a)-TaS2 powder (1.91 g about 0.008 mole) is placed in a Pyrex tube about 20 cm long and 1 cm in diameter, with a 2-mm wall thickness. An excess of redistilled pyridine is then added. The volume of pyridine should be three or four times that of the TaS2 powder. ("Caution. Direct contact with pyridine or pyridine vapor should be avoided.) The tube is connected to avacuum system and is quickly pumped down to 15 torr pressure (vapor pressure of liquid pyridine at room temperature). The pyridine is then frozen with liquid nitrogen, and the evacuation is continued to a pressure of 10 3 torr. To remove dissolved air,... 

Caution. The vapor pressure of liquid NH3 at room temperature is 8 atm. The seal on the Pyrex tube should be carefully annealed so that the tube will not explode. The sealed tube always should be kept behind a protective shield or in a protective metal pipe. 

---