Intermolecular Forces and Liquids

Intermolecular forces and liquids. Based on intermolecular interactions, which of the following should have the highest boiling point? a) CH4 b) C2H5OH c) H2S d) CH3OH e) CHCl3 ************************************************************** Which of the following substances would show Dipole-Dipole intermolecular forces? SiF4, CHCI3, CO2, SO2, H2S a) only H2S b) SiF4, CHC13 and SO2 d) SO2, CHCl3 and H2S c) SO2 and CO2 e) only CHC13 ************************************************************** Which of the following compounds can form hydrogen bonding? a) CH3CH2OH b) CHL c) CH3COCH3 d) CHC13 e) F- ************************************************************** Which of the following liquids has the highest critical temperature? a) CH3OCH3 b) CH2CH2 d) CH3Br c) C2H5OH e) HOCH2CH2OH ************************************************************** Which of these compounds can form H- bonds among themselves? H2S, HF, (CH3)3N and CH3NH2 a) CH3NH2 and (CH3)3N b) CH3NH2 and H2S c) (CH3)3N and HF d) HF and CH3NH2 e) H2S, (CH3)3N and CH3NH2 ************************************************************** Among the following, the compound with the lowest vapor pressure is: ************************************************************** Which of the following substances would show only dispersion (London) forces? CH2Cl2, CS2, SO2, PCI3, PF5 a) Only CS2 b) Only CH2Cl2 and CS2 d) Only CS2 and PF5 c) Only CH2Cl2, CS2 and PF5 e) All five compounds ************************************************************** Which of the following compounds can not form hydrogen bonding with water? O a) CH3-O-CH3 b) CHCl3 ‖ c) CH3-C-CH3 e) CH3OH ************************************************************** Which of the following compounds would have highest vapor pressure? a) PH3 d) CH2(OH)-CH2(OH) b) NH3 c) H2O e) CH2(NH2)-CH2(NH2) ************************************************************** Which of these compounds is expected to have the highest normal boiling point? a) CH4 b) NH3 c) He d) PH3 e) Ne ************************************************************** Which of the following properties indicates the presence of weak intermolecular forces in a liquid? a) High boiling point c) Low vapor pressure e) High surface tension b) Low heat of vaporization d) High viscosity ************************************************************** Given the following materials: NH3, CH2OHCH2OH, SO2, HCl, CH4, HF, H2O, He Which of the following statements is correct? a) CH4 has the highest boiling point. b) CH2OHCH2OH has the highest vapor pressure. c) HF has the highest surface tension. d) HCl has the highest surface tension. e) He has the lowest boiling point. ************************************************************** According to kinetic molecular theory, which of the following statements is correct. a) Volume occupied by liquid molecule is negligible and intermolecular forces between liquid molecules are very weak. b) Liquid molecules are in random motion and at certain temperature all liquid molecules have same kinetic energy. c) All liquids have same average kinetic energy at same temperature. d) Gas, liquid and solid molecules have same kinetic energy at same temperature. e) Solid molecules are in random motion and slide on each other. A liquid boiling when it is: a) vapor pressure is exactly 1.0 atm. b) vapor pressure is equal to or greater than the external pressure. c) temperature is equal to 273 K (standard temperature). d) temperature is greater than room temperature. e) temperature is above its critical temperature. ************************************************************** Which of the following indicates the existence of strong intermolecular forces in liquid phase? a) Low viscosity b) High boiling point d) Low surface tension c) High vapor pressure e) low heat of vaporization ************************************************************** Decreasing the external pressure will: a) Increase the vapor pressure of a liquid. b) Markedly decrease the freezing point of a liquid. c) Increase the boiling point of a liquid. d) Weaken the intermolecular forces in a liquid. e) Decrease the boiling point of a liquid. ************************************************************** Which of the following statements is FALSE? a) A phase diagram is a pressure-temperature plot which outlines the P-T regions of stability of a molecule in its solid, liquid and gaseous. b) The vapor pressure of a liquid is lower than the external pressure at temperatures below its boiling point. c) Ice has a lower density than liquid water. d) Water boils at a higher temperature atop mountain Everest than on sea level. e) Water has a lower vapor pressure than ammonia (NH3) at the same temperature. Consider the following compounds: CH3CH2OH, CH3OH, CH3CH2-O-CH2CH3 and CH4 -The correct order of increasing in their vapor pressures is: a) b) c) d) e) CH3CH2OH < CH3CH2-O-CH2CH3 < CH4 < CH3OH CH3CH2OH < CH3CH2-O-CH2CH3 < CH3OH < CH4 CH4 < CH3CH2-O-CH2CH3 < CH3OH < CH3CH2OH CH4 < CH3OH < CH3CH2-O-CH2CH3 < CH3CH2OH CH3CH2OH < CH3OH < CH3CH2-O-CH2CH3 < CH4 ************************************************************** Arrange the following liquids in order of increasing vapor pressure at the same temperature: dimethyl ether (CH3OCH3), propane (C3H8) and ethanol (CH3CH2OH) a) b) c) d) e) ethanol < propane < dimethyl ether propane < ethanol < dimethyl ether dimethyl < ether ethanol < propane ethanol < dimethyl ether < propane propane < dimethyl ether < ethanol ************************************************************** The vapor pressure of ethanol is 291 mmHg at 69.5oC. Its molar heat of vaporization is 39.5 kJ/mol. What is vapor pressure of ethanol. In mmHg, at 49.5oC ? a) 123 b) 192 c) 455 d) 291 e) 760 ************************************************************** The vapor pressure of a certain liquid is 42.0 mmHg at 10.0oC. Calculate its vapor pressure in (mmHg) at 52.0oC. The molar heat of vaporization of the liquid is 31.0 kJ/mol. a) 109 b) 160 c) 231 d) 32 e) 760 ************************************************************** The molar heat of vaporization of a liquid is 32.0 kJ/mol and its vapor pressure is 27.0 mmHg at 10.0 oC. Calculate it vapor pressure (in mn mmHg) at 50.0 °C. a) 226 b) 280 c) 334 d) 426 e) 388 ************************************************************** The compound CH3Cl has a vapor pressure of 105 mmHg at 212 K and 14.0 mmHg. Calculate the heat of vaporization of CH3Cl in KJ/mol. a) 21.5 b) 15.3 c) 30.5 d) 45.4 e) 5.91 ************************************************************** The molar heat of vaporization of a liquid is 36.0 kJ/mol, and its vapor pressure is 455 mmHg at 75.0oC. Calculate the vapor pressure (in mmHg) at 85.0oC? a) 644 b) 585 c) 760 d) 701 e) 524 ************************************************************** The vapor pressure of a water is 42.2 mmHg at 35.0 °C. Calculate its vapor pressure in (mmHg) at 55.0 °C. The molar heat of vaporization of the water is 40.7 kJ/mol. a) 69.8 b) 32.0 c) 111 d) 173 e) 760. ************************************************************** Consider the given phase diagram. The phase change from A to B is: a) Sublimation b) Melting c) Condensation d) Vaporization e) Freezing consider the phase diagram given in question 6 above, which of the following statements is correct? a) The normal boiling point of the compound is -28 °C. b) The compound can be sublimed if heated at pressure lower than 0.50 atm. c) The compound can be sublimed if heated at pressure greater than 0.50 atm. d) The density of the liquid state is greater than that of the solid state. e) The triple point temperature is higher than -28 °C. ************************************************************** In the phase diagram below, which of the following statements is correct? a) b) c) d) e) The point D corresponds to the melting point. The change from point A to point G corresponds to freezing. The point B corresponds to the critical point. The density of the solid is greater than the density of liquid. The point F corresponds to the normal boiling point. Consider the phase diagram for a substance X: -Which of the following statements is correct? a) At the temperature lower than -25oC, The substance X can not exist at the liquid state at any applied pressure. b) Cooling substance X in the vapor state at 2 atm convert the substance from vapor to liquid. c) The freezing point of substance X decreases as pressure increases. d) At temperature higher than -25oC, substance X can not exist in the solid state at any applied pressure. e) The density of the liquid substance X is greater than that of the solid state. ************************************************************** Consider the given phase diagram. -The phase change from D to E is: a) Sublimation b) Melting c) Condensation d) Vaporization e) Freezing ************************************************************** Which of the following statement is correct? a) The boiling point of water is always 100oC b) The normal boiling point is the temperature at which the liquid's vapor pressure equals the external atmospheric pressure. c) The normal boiling point is the temperature at which the intermolecular attraction forces in the vapor equal those in the liquid. d) The normal boiling points of all liquids decrease as the external pressure increases. e) The normal boiling point is the temperature at which the liquid's vapor pressure equals standard atmospheric pressure. ************************************************************* What pressure would be required to liquefy (or condense) a sample of water vapor at oC? a) b) c) d) 0.0060 atm 1.00 atm 218 atm No amount of pressure can bring about the change of H2O vapor to liquid at 500oC. e) Some pressure higher than 218 atm but which cannot be determined from the phase diagram. ************************************************************* Which of the following statements is correct? a) The freezing point of all liquids decrease as the external pressure increases b) The boiling point of water is always 100.0 °C c) The freezing point of water decreases as the external pressure increases. d) The normal boiling point is the temperature at which the intermolecular attractive forces in the vapor phase equal those in the liquid phase. e) The freezing point of water is always 0.0 °C