Vapor pressure of benzene and toluene

What is the vapor pressure of each component at 25°C and the total vapor pressure of a mixture in which one-third of the molecules are benzene (so Xben/ene,liquid = 3 and xtoiuene,iiqUid = ) The vapor pressures of benzene and toluene at 25°C are 94.6 and 29.1 Torr, respectively. 

Assume that the mixture of benzene and toluene obeys Raoult s Law and the molar mass in kilograms occupies 22.4 m3 in the vapor phase at standard conditions. The molar masses of benzene and toluene are 78 and 92 respectively. The vapor pressures of benzene and toluene at 25°C are 0.126 bar and 0.0376 bar respectively. 

The vapor pressures of benzene and toluene at 90°C are 1034 and 413 torr, respectively. What is the mole fraction of benzene in the benzene-toluene solution that boils at 90°C ... 

Benzene and toluene form ideal solutions. Consider a solution of benzene and toluene prepared at 25°C. Assuming that the mole fractions of benzene and toluene in the vapor phase are equal, calculate the composition of the solution. At 25°C the vapor pressures of benzene and toluene are 95 and 28 torr, respectively. 

The vapor pressures of benzene and toluene at 80°C are determined from the Antoine equation to be 757.7 mm Hg and 291.2 mm Hg, respectively. Assuming that nitrogen is insoluble in the condensate. Equation 6.4-8 gives... 

Assume that the vapor pressures of benzene and toluene are given by the Antoine equation. Table 6.1-1 that Raoult s law—Equation 6.4-1—applies and that the enthalpies of benzene and toluene liquid and vapor are linear functions of temperature. Specific enthalpies at two temperatures are given here for each substance in each phase. 

Raoult s law may be used to determine phase compositions for the binary system benzene-toluene, at low temperatures and pressures. Determine the composition of the vapor in equilibrium with a liquid containing 0.4 mole fraction of benzene at 300 K, and calculate the total equilibrium pressure. Estimate the vapor pressure of benzene and toluene at 300 K from the Antoine equation,... 

Calculate the mole fraction of each species in the vapor phctse and liquid phase, respectively, as well as i2, assuming ideal liquid solution and ideal gas behavior. The following information is available (1) tbe vapor pressures of N2 and O2 at 90 K are 3.53 atm and 750 mm Hg, respectively (Rubemann, 1949) (2) tbe vapor pressures of benzene and toluene at 100 °C are 1.78 atm and 0.73 atm, respectively (3) the vapor pressures of ethylbenzene and styrene are 0.166 atm and 0.119 atm, respectively. State your assumptions. 

Figure 6.1 The Partial Vapor Pressures of Benzene and Toluene in a Solution at 80°C. Drawn from data of M. A. Rosanoff, C. W. Bacon, and R W. Schulze, J. Am. Chem. Soc., 36, 1993 (1914).

Substances with similar molecules usually form nearly ideal solutions. Toluene and benzene are an example. Figure 6.1 shows the partial vapor pressures of benzene and toluene and the total vapor pressure in a solution at 80 C, plotted as functions of the mole fraction of benzene. The line segments in the figure correspond to Raoult s law, which is very nearly obeyed. 

Here we calculate the vapor pressures of benzene and toluene at 20°C using the Antoine equation (see Chapter 5) and Table A.2. For benzene... 

At 1 atm (760 torr) pressure, the normal boiling points of benzene and toluene are 80.1 and 110.6°C. Benzene and toluene may be assumed to form ideal liquid solutions. The vapor pressures of benzene and toluene at these temperatures are as follows ... 

Calculate the total pressure of benzene and toluene over a solution of 0.661 mol benzene and 0.227 mol toluene at 25°C. Their vapor pressures when pure are 96.0 torr and 27.0 torr, respectively. 

Benzene and toluene form a nearly ideal solution. If the vapor pressure for benzene and toluene at 25°C is 94 mm Hg and 29 mm Hg respectively, what is the approximate vapor pressure of a solution made from 25% benzene and 75% toluene at the same temperature ... 

FIGURE 12.8 The dependence of the partial pressures of benzene and toluene on their mole fractions in a benzene-toluene solution fX c /uene I X en enei 80°C. This solution is said to be ideal because the vapor pressures obey Raoult s law. 

By use of the following vapor pressures for benzene and toluene [taken from The Chemical Engineer s Handbook, 2d ed., J. H. Perry (ed.) McGraw-... 

Figure 14.11 shows the vapor pressure versus mole fraction of benzene for the benzene-toluene system, which behaves ideally to a good degree of accuracy over the entire range of composition. The partial pressures of benzene and toluene, also shown in the figure, are linear functions of the mole fraction of benzene, since Raoult s law is obeyed. 

Strategy Assuming that the mixture of benzene and toluene is an ideal solution, the partial pressures of both benzene and toluene can be calculated using Raoult s law (Equation 9.8). To do this we need to convert grams of both benzene and toluene to moles and then determine the mole fractions, (a) The total vapor pressure is then obtained by adding together the partial pressures of benzene and toluene, (b) The mole fractions of benzene and toluene in the vapor phase can be determined from the partial pressures using Dalton s law. 

It is assumed that the bottom is pure toluene and the distillate is pure benzene. This is a good assunption for estimating top and bottom pressures given the mole fractions specified for the distillate and bottoms. Therefore, at the bottom temperature of 141.7°C, the vapor pressure of toluene, and hence the pressure at the bottom of the column, is 227.2 kPa. At the top temperature of 104.2°C, the vapor pressure of benzene, and hence the pressure at the top of the column, is 204.8 kPa. 

Consider now a vapor mixture of benzene and toluene at a mole fraction of 0.5 for both and a total pressure of 1 atmosphere (760 mmHg). We would like to calculate the dew-point temperature for such a vapor mixture. For simplicity, we will assume an ideal gas mixture. In other words, the fugacity coefficient for either component will be set to one = 10 ... 

Self-Test 8.16B What is the total vapor pressure at 25°C of a mixture of equal masses of benzene and toluene ... 

Self-Test 8.17A (a) Determine the vapor pressure at 25°C of a solution of toluene in benzene in which the mole fraction of benzene is 0.900. (b) Calculate the mole fractions of benzene and toluene in the vapor. 

The normal boiling point of a binary liquid mixture is the temperature at which the total vapor pressure is equal to 1 atm. If we were to heat a sample of pure benzene at a constant pressure of 1 atm, it would boil at 80.1°C. Similarly, pure toluene boils at 110.6°C. Because, at a given temperature, the vapor pressure of a mixture of benzene and toluene is intermediate between that of toluene and benzene, the boiling point of the mixture will be intermediate between that of the two pure liquids. In Fig. 8.37, which is called a temperature-composition diagram, the lower curve shows how the normal boiling point of the mixture varies with the composition. 

Benzene, C6Hh, and toluene, C(,H5CH5, form an ideal solution. The vapor pressure of benzene is 94.6 Torr and that of toluene is 29.1 Torr at 25°C. Calculate the vapor pressure of each of the following solutions and the mole fraction of each substance in the vapor phase above those solutions at 25°C ... 

Figure 4.3 Vapor-liquid equilibrium for a binary mixture of benzene and toluene at a pressure of 1 atm. (From Smith R and Jobson M, 2000, Distillation, Encyclopedia of Separation Science, Academic Press reproduced by permission).

Although the starting liquid mixture of benzene and toluene has a 1 1 molar composition, the composition of the vapor is not 1 1. Of the 760 mm Hg total vapor pressure for the boiling mixture, 542/760 = 71.3% is due to benzene and 218/760 = 28.7% is due to toluene. If we now condense the vapor, the liquid we get has this same 71.3 28.7 composition. On boiling this new liquid mixture, the composition of the vapor now becomes 86.4% benzene and 13.6% toluene. A third condense/boil cycle brings the composition of the vapor to 94.4% benzene/5.6% toluene, and so on through further cycles until the desired level of purity is reached. 

Curve ABC in each figure represents the states of saturated-liquid mixtures it is called the bubble-point curve because it is the locus of bubble points in the temperature-composition diagram. Curve ADC represents the states of saturated vapor it is called the dewpoint curve because it is the locus of the dew points. The bubble- and dew-point curves converge at the two ends, which represent the saturation points of the two pure components. Thus in Fig. 3.6, point A corresponds to the boiling point of toluene at 133.3 kPa, and point C corresponds to the boiling point of benzene. Similarly, in Fig. 3.7, point A corresponds to the vapor pressure of toluene at 100°C, and point C corresponds to the vapor pressure of benzene. 

FIGURE 8.1 Vapor pressures of benzene, toluene, and xylene (Example 8.1). Note 1 mmHg = 0.133 kPa. 

Calculate the vapor pressure of benzene, CgHg, at 25°C in an ideal solution containing 1.66 mol of benzene and 0.313 mol of toluene. The vapor pressure of pure benzene is 96.0 torr. 

A liquid mixture of benzene and toluene containing 50.0 wt% benzene at 90 C and pressure Po is fed at a rale of 32.5 m /h into a flash evaporator, a heated tank maintained at a pressure P,ank Po-When the feed is exposed to the reduced pressure in this unit, a portion of it evaporates. The liquid and vapor product streams are in equilibrium at 75 C and P,ank- liquid product contains 43.9 mole% benzene. When carrying out the requested calculations, assume volume additivity of liquid benzene and toluene, use Raoult s law and the Antoine equation where necessary, and neglect the effect of pressure on enthalpy. 

At 20°C, the vapor pressure of toluene is 0.0289 atm and the vapor pressure of benzene is 0.0987 atm. Equal numbers of moles of toluene and benzene are mixed and form an ideal solution. Compute the mole fraction of benzene in the vapor in equilibrium with this solution. 

Benzene and toluene combine to form an ideal solution. At 80°C, vapor pressure of pure benzene is 800 mmHg and the vapor pressure of pure toluene is 300 mmHg. If the vapor pressure of the solution is 400 mmHg, what are the mole fractions of benzene and toluene ... 

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