Question

All 3 5A7 8 and 9

e of at - ent U lable 4C.1 to calculate the vapor pressure of bo melcury at 275 K. SA.7 The vapor pressure of boron trichloride at- and its enthalpy of vaporization is 23 mal boiling point of boron trichloride? 5A .77 kJ mol- . What is the nor- ar 5A.8 The vapor pressure of dimethyl ether at -58 °C is 18.1 kPa and its enthalpy of vaporization is 21.51 kJ mol'. What is the normal boiling point of dimethyl ether? i 5A.9 Arsine, AsH, is a highly toxic compound used in the elec- tronics industry for the production of semiconductors. Its vapor pressure is 35 Torr at-1 11.95 ? and 253 Torr at-83.6? Using these data, calculate (a) the standard enthalpy of vaporization

Answer 1

5A.7 At normal boiling point Vapour pressure = external pressure = 101.325kpa Using Clausivs clapeyron equation ln(P_1/P_2) = delta H_2/R[1/T_2-1/T_1] where P_1 = 17.0kpa P_2 = 101.325kpa delta H_v = 23.77Ks/mol = 23.77 times 10^3J/mol R = 8.314J/mol.k T_1 = -28 degree C = (273.15-28)K = 245.15K implies ln(17.0kpa/101.325kpa) = 23.77 times 10^3J/mol/8.3145J/mol.K[1/T_2-1/245.15K] implies -1.785 = 2859.033[1/T^2-1/245.15k] implies -6.243 times 10^-4K = 1/T_2-1/245.15k implies 3.455 times 10^-3 = 1/T_2 implies T_2 = 289.45K T_2 = 16.3 degree C Normal Boiling point of Boron trichloride is 16.3 degree C \r\n similarly as Q_SA.7 ln(P_1/P_2) = delta H_v/R(1/T_2-1/T_1) here P_1 = 18.1kpa P_2 = 101.325kpa delta H_v = 21.51KJ/mol = 21.51 times 10^3J/mol R = 8.314J/mol.k T_1 = -58 degree C = (273.15-58)K = 215.15K implies ln(18.1kpa/101.325kpa) = 21.51 times 10^3J/mol/8.314J/mol.k(1/T_2-1/215.15) implies -6.66 times 10^-4 = 1/T_2-1/215.15 implies 3.98 times 10^-3 = 1/T_2 or T_2 = 251.12K T_2 = -22.03 degree C Normal Boiling point of dimethyl either is -22.03 degree C Again using