Chapter 8, Problem 8.21NP

The vapour pressure of a substance at 20.0 °C is 58.0 kPa and its enthalpy of vaporization is 32.7 kJ mol−1. Estimate the temperature at which its vapour pressure is 66.0 kPa.

A handbook lists the normal boiling point of isooctane, a gasoline component, as 99.2ºC and its enthalpy of vaporization as 35.76 kJ mol-1. Calculate the vapor pressure of isooctane at 25ºC.

Estimate the freezing point (solidification temperature) of benzene at a pressure of 115 bar given that the enthalpy of fusion (AH,jus) of benzene is 9.94 kJ/mol. The corresponding densities of liquid and frozen benzene are 876 kg/m? and 894 kg/m? respectively.

The vapor pressures of tetrachloromethane (A) and trichloroethylene (B) between 76.8 °C and 87.2 °C are given by the empirical formulas 2790.78 In(P/torr)=15.8401– T+226.4 and 2345.4 In(P / torr)=15.0124 – T+192.7 where T is the Celsius temperature. Compute the values of XA and ya at 82.0 °C. Assume an ideal solution with a total vapor pressure of 1 atm.

At 25 °C, the equilibrium vapour pressure of ethanol is 0.0821 bar. The standard enthalpy of vapourization is 39.28 kJ/mol. What is the boiling point of ethanol at standard pressure? In other words, at what temperature does the equilibrium vapour pressure of ethanol reach 1.000 bar? Report your answer in degrees Celsius, but do not include the units in the answer. Report your answer to the nearest degree.

The variation of vapor pressure of diethyl ether with temperature at its normal boiling temperature (34.7°C) was found to be 3533 Pa K-1. Calculate the enthalpy of vaporization of diethyl ether.

Camphor 1C10H16O2 melts at 179.8 °C, and it has a particularly large freezing-point-depression constant, Kf = 40.0 °C>m. When 0.186 g of an organic substance of unknown molar mass is dissolved in 22.01 g of liquid camphor, the freezing point of the mixture is found to be 176.7 °C. What is the molar mass of the solute?

3. A 12.0 cm3 sample of liquid H2O (density 1.00 g.cm-3) is heated to 328 oC under an external pressure of 0.8 atm, conditions under which it vapourises: (i)  Calculate the volume of the gas. (ii)  Calculate the mass of the same volume (as in part i) of CO2 gas under the same conditions. (iii)  Calculate temperature of that sample of CO2 (as in part ii) at 8.0 atm pressure in a 20.0 L container.

At 25 °C, the equilibrium partial pressures for the reaction 2 A(g) + 2 B(g) = C(g) + 3 D(g) were found to be PA = 4.41 bar, PB 5.54 bar, Pc = 4.92 bar, and P, = 5.18 bar. What is the standard change in Gibbs free energy of this reaction at 25 °C? kJ/mol