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18 Nov 2019
Chem 301 Fall, 2017 HW 7 (Due 10/18/17)- Note: You will need to use data from Tables 2C.1- 2C.5 to answer some of these questions. You MUST include a printout of the graph required to do question (8) to receive credit for this Hw (1) The densities of a given solid and liquid of molar mass 122.5 g mol at its normal melting temperature of 427.15 K are 1075 and 1012 kg m, respectively. If the pressure is increased to 120 bar, the melting temperature increases to 429.35 K. Calculate AnsHP and Ass-for this substance (2) Benzenel) has a vapor pressure of 0.1269 bar at 298.15K. Calculate the vapor pressure of CsHs(l) at 340.0 K assuming: (a) that the enthalpy of vaporization does not change with temperature; (b) that the enthalpy of vaporization at temperature T can be calculated from the equation: Î111pH(T)-4,apa(7,) + &C, (T-%) assuming ACp does not change with temperature (3) Use the vapor pressures for tetrachloromethane given in the following table to estimate the temperature and pressure of the triple point and also the enthalpies of fusion, vaporization and sublimation. Solid 230 225.7 Liquid 280 340 6440 62501 (4) Calculate the change in the freezing point of water at 100. and 500. bar compared to that at 1 bar assuming that the density of the liquid and solid phases remain constant at 997 and 917 kg m, respectively. Explain why your answer is positive (or negative) (5) Freeze-drying occurs when vapor (and thus heat) is removed from a liquid. Assuming the vapor pressure of H2O remains constant as it cools, estimate the mass of ice that will form as H20 vapors are pulled off of 500.0 g of H20 (1) starting at 25.0°C (6) In vacuum distillation, the surrounding pressure inside a chamber is lowered so the solvent boils at a lower temperature. This is useful when isolating compounds that are temperature sensitive. To what pressure must a chamber be reduced to distill methanol at 25.0°C?
Chem 301 Fall, 2017 HW 7 (Due 10/18/17)- Note: You will need to use data from Tables 2C.1- 2C.5 to answer some of these questions. You MUST include a printout of the graph required to do question (8) to receive credit for this Hw (1) The densities of a given solid and liquid of molar mass 122.5 g mol at its normal melting temperature of 427.15 K are 1075 and 1012 kg m, respectively. If the pressure is increased to 120 bar, the melting temperature increases to 429.35 K. Calculate AnsHP and Ass-for this substance (2) Benzenel) has a vapor pressure of 0.1269 bar at 298.15K. Calculate the vapor pressure of CsHs(l) at 340.0 K assuming: (a) that the enthalpy of vaporization does not change with temperature; (b) that the enthalpy of vaporization at temperature T can be calculated from the equation: Î111pH(T)-4,apa(7,) + &C, (T-%) assuming ACp does not change with temperature (3) Use the vapor pressures for tetrachloromethane given in the following table to estimate the temperature and pressure of the triple point and also the enthalpies of fusion, vaporization and sublimation. Solid 230 225.7 Liquid 280 340 6440 62501 (4) Calculate the change in the freezing point of water at 100. and 500. bar compared to that at 1 bar assuming that the density of the liquid and solid phases remain constant at 997 and 917 kg m, respectively. Explain why your answer is positive (or negative) (5) Freeze-drying occurs when vapor (and thus heat) is removed from a liquid. Assuming the vapor pressure of H2O remains constant as it cools, estimate the mass of ice that will form as H20 vapors are pulled off of 500.0 g of H20 (1) starting at 25.0°C (6) In vacuum distillation, the surrounding pressure inside a chamber is lowered so the solvent boils at a lower temperature. This is useful when isolating compounds that are temperature sensitive. To what pressure must a chamber be reduced to distill methanol at 25.0°C?
Lelia LubowitzLv2
18 Nov 2019