SOLVED

71) The maximum temperature at which a gas can be liquefied is just below the ________. A) boiling temperature B) critical temperature C) melting temperature D) normal temperature E) superheating temperature 72) Liquid and vapor phases of a substance become indistinguishable at the ________. A) triple point B) normal point C) permanent point D) critical point E) absolute point 73) The relationship between the vapor pressure of a liquid and temperature can be expressed by the Clausius-Clapeyron equation: Log[P2/P1] = [ΔHvap/R] × [1/T1 – 1/T2] Ethanol (C2H5OH) has a normal boiling point of 78.3°C and, with ΔHvap = 39.3 kJ/mol. What is the vapor pressure of ethanol at 50.0°C? A) 118 torr B) 234 torr C) 354 torr D) 485 torr E) 670 torr 74) Arrange the following compounds in order of increasing viscosity: I)1-propanol, CH3CH2CH2OH; II)1,2-propanediol, CH3CH(OH)CH2OH; III)1,2,3-propanetriol, (glycerol), HOCH2CH(OH)CH2OH. A) I, II, III B) II, III, I C) III, I, II D) III, II, I E) I, III, II 75) Arrange the following compounds in order of increasing boiling point: I)1-propanol, CH3CH2CH2OH; II)1,2-propanediol, CH3CH(OH)CH2OH; III)1,2,3-propanetriol, (glycerol), HOCH2CH(OH)CH2OH. A) II, III, I B) I, II, III C) III, I, II D) III, II, I E) I, III, II 76) A 0.90 g sample of liquid water was introduced into an evacuated 2.00 L flask, which was then sealed and heated to 37°C. What percentage, by mass, of the water remained as liquid? [Vapor pressure of water at 37°C = 48.2 torr.] A) 10% B) 18% C) 82% D) 90% E) 0% 77) What would be the appropriate equilibrium temperature of a system obtained by adding 25.0 g of ice at 0°C to 250.0 mL of “hot” (80°C) coffee, assuming that the heat capacity and density of the coffee are the same as for pure water (4.18 J g-1 °C-1 and 0.997 g mL-1), and also assuming negligible heat transfer with the surroundings? [For water, ΔHfusion = 6.02 kJ/mol.] A) 33°C B) 40°C C) 65°C D) 73°C E) 79°C 78) The factor that has the largest effect on vapor pressure is ________. A) liquid surface area B) molecular dipole moment C) presence of H bonding D) liquid mole weight E) volume available for vapor 79) The heat of deposition equals the negative of the heat of ________. A) fusion B) condensation C) sublimation D) solidification E) reposition 80) A substance has a heat of fusion of 61.5 kJ/mol and a heat of deposition of -167.4 kJ/mol. What is the heat of sublimation in kJ/mol? A) -61.5 kJ/mol B) 61.5 – 167.4 kJ/mol C) 61.5 + 167.4 kJ/mol D) 167.4 – 61.5 kJ/mol E) 167.4 kJ/mol