Q&A Hero

Q: Hydrogen bonding is present in all of the following molecular solids EXCEPT ____. A.H2SO4 (dihydrogen sulfate) B.CH3OH (methanol) C.CH3OCH3 (dimethyl ether) D.HF (hydrogen fluoride) E.CH3CO2H (acetic acid)

Q: Which one of the following molecules will exhibit dipole-dipole intermolecular forces as a pure liquid? A.CS2 B.C2H2 C.CCl4 D.Br2 E.PH3

Q: Which one of the following sets of ions are listed in order of lowest to highest hydration energy? A.H+ < Na+ < Mg2+ B.Mg2+ < Ca2+ < Ba2+ C.Mg2+ < Ba2+ < Ca2+ D.Ca2+ < K+ < Rb+ E.Rb+ < K+ < Ca2+

Q: Place the following cations in order from the lowest to the highest hydration enthalpy: K+, Ca2+, and Mg2+. A.K+ < Ca2+ < Mg2+ B.Mg2+ < Ca2+ < K+ C.Ca2+ < K+ < Mg2+ D.Ca2+ < Mg2+ < K+ E.Mg2+ < K+ < Ca2+

Q: Place the following cations in order from lowest to highest hydration enthalpy: H+, K+, and Cs+. A.K+ < Cs+ < H+ B.Cs+ < H+ < K+ C.Cs+ < K+ < H+ D.H+ < K+ < Cs+ E.H+ < K+ < Na+

Q: Which of the following statements concerning the attraction of ions to polar molecules is/are CORRECT? 1/ The energy of attraction between an ion and a polar molecule is inversely proportional to the square of the distance between the center of the ion and the oppositely charged pole of the dipole. 2/ The higher the ion charge, the stronger the attraction between the ion and a polar molecule. 3/ The greater the magnitude of the dipole, the greater the attraction between the ion and a polar molecule. A.1 only B.2 only C.3 only D.2 and 3 E.1, 2, and 3

Q: Two important allotropes of phosphorus are white phosphorus and red phosphorus. White phosphorus, P4, has a melting point of 44.1 C and spontaneously reacts with oxygen. Red phosphorus, a network solid, melts at 280 C and is stable in air. Use your knowledge of intermolecular and intramolecular bonding to explain why these two forms of the same element have such different properties.

Q: Which ion, K+ or Ca2+, is expected to have the more negative enthalpy of hydration? Why?

Q: The ________ equation relates the equilibrium vapor pressure of a volatile liquid to the molar enthalpy of vaporization at a given temperature.

Q: Above its critical temperature and pressure, a substance becomes a(n) ________ fluid.

Q: ________ is a measure of the degree to which the electron cloud surrounding an atom or molecule can be distorted in an electric field.

Q: When a glass tube with a small diameter is placed in water, the water rises in the tube. This is known as ________ action.

Q: A cup of oil takes longer to pour from a glass than a cup of water. A liquid's resistance to flow is referred to as its ________.

Q: Which of the following are valid reasons why vegetable oil has a greater viscosity than diethyl ether, CH3OCH3? 1/ Oil molecules have long chains that become entangled. 2/ Unlike diethyl ether, oil molecules are not held together by hydrogen bonds. 3/ Intermolecular forces are greater for the larger oil molecules. A.1 only B.2 only C.3 only D.1 and 3 E.2 and 3

Q: The toughness of the skin of a liquid is a measure of its ____. A.meniscus curvature B.adhesive forces C.cohesive forces D.viscosity E.surface tension

Q: Which of the following statements concerning a supercritical fluid (SCF) is/are CORRECT? 1/ An SCF has a density similar to that of a gas. 2/ An SCF has a viscosity similar to that of a liquid. 3/ An SCF fills its entire container, much like a gas. A.1 only B.2 only C.3 only D.1 and 3 E.1, 2, and 3

Q: Normal boiling point is defined as A.the temperature at which the vapor pressure of a liquid equals 1 atm. B.the pressure at which any liquid boils at 373.15 K. C.the temperature at which water boils in a vacuum. D.the temperature at which the liquid and gaseous phases of a substance have equal densities. E.the temperature at which the enthalpy of vaporization equals 100.0 kJ/mol.

Q: Which of the following phase transitions is/are endothermic?1/ liquid water freezing to a solid at its normal freezing point of 0.0 C.2/ the sublimation of solid carbon dioxide into the gas phase.3/ gaseous sulfur dioxide condensing into a liquid at its boiling point of -10.0 C.A.1 onlyB.2 onlyC.3 onlyD.1 and 2E.1, 2, and 3

Q: Which of the following properties of water can be attributed to hydrogen bonding? 1/ high melting point 2/ high heat of vaporization 3/ low vapor pressure 4/ high surface tension A.1 and 3 B.2 and 3 C.2, 3, and 4 D.1, 3, and 4 E.1, 2, 3, and 4

Q: Which of the following statements is/are CORRECT? 1/ If the intermolecular forces in a liquid decrease, the normal boiling point of the liquid decreases. 2/ If the temperature of a liquid increases, the equilibrium vapor pressure increases. 3/ If the surface area of a liquid increases, the equilibrium vapor pressure of the liquid increases. A.1 only B.2 only C.3 only D.1 and 2 E.1, 2, and 3

Q: Freon-113, C2Cl3F3, has an enthalpy of vaporization of 27.0 kJ/mol and a normal boiling point of 48.0 C. What is the vapor pressure (in atm) of Freon-113 at 22.0 C? (R = 8.314 J/Kmol) A. 0.21 atm B. 0.35 atm C. 0.41 atm D. 0.46 atm E. 4.4 atm

Q: Mount Everest rises to a height of 8.850 103 m above sea level. At this height, the atmospheric pressure is 231 mm Hg. At what temperature (in C) does water boil at the summit of Mount Everest? The vapor pressure of water at 373 K is 760.0 mm Hg. (DvapH for H2O = 40.7 kJ/mol and R = 8.314 J/Kmol) A.4.07 C B.69.0 C C.72 C D.87 C E.364 C

Q: Xenon has an enthalpy of vaporization of 12.6 kJ/mol and a vapor pressure of 1.00 atm at -108.0 C. What is the vapor pressure of xenon at -148.0 C? (R = 8.314 J/Kmol)A.0.053 atmB.0.73 atmC.0.93 atmD.0.99 atmE.19 atm

Q: Sulfur dioxide has a vapor pressure of 462.7 mm Hg at -21.0 C and a vapor pressure of 140.5 mm Hg at -44.0 C. What is the enthalpy of vaporization of sulfur dioxide? (R = 8.314 J/Kmol)A.0.398 kJ/molB.6.33 kJ/molC.14.0 kJ/molD.24.9 kJ/molE.39.8 kJ/mol

Q: Ethanol has an enthalpy of vaporization of 42.3 kJ/mol. The compound has a vapor pressure of 1.00 atm at 78.3 C. At what temperature is the vapor pressure equal to 0.800 atm? (R = 8.314 J/Kmol)A.-83.8 CB.-24.4 CC.62.6 CD.73.0 CE.78.0 C

Q: A linear relationship exists between the natural logarithm of the vapor pressure of a gas and the reciprocal of its temperature (in kelvin). What is the slope of the line? A. B. C.T D. E.

Q: If 3.01 g of water is sealed in an evacuated 2.00 L flask and heated to the normal boiling point of 373 K, what is the pressure in the flask? (R = 0.08206 Latm/molK) A.0.391 atm B.0.678 atm C.1.00 atm D.2.56 atm E.46.1 atm

Q: At 75.0 C, water has an equilibrium vapor pressure of 289.1 mm Hg. If 4.22 g H2O is sealed in an evacuated 5.00 L flask and heated to 75.0 C, what mass of H2O will be found in the gas phase when liquid-vapor equilibrium is established? Assume any liquid remaining in the flask has a negligible volume. (R = 0.08206 Latm/molK, 1 atm = 760 mm Hg) A.0.240 g B.1.20 g C.2.64 g D.3.02 g E.4.22 g

Q: At its boiling point of 58.8 C, 3.66 kJ of heat is required to vaporize 19.5 g of bromine (Br2). What is the molar enthalpy of vaporization of bromine? A.0.447 kJ/mol B.10.0 kJ/mol C.30.0 kJ/mol D.44.7 kJ/mol E.71.4 kJ/mol

Q: Ammonia, NH3, is used as a refrigerant. At its boiling point of -33 C, the standard enthalpy of vaporization of ammonia is 23.3 kJ/mol. How much heat is released when 50.0 g of ammonia is condensed at -33 C?A.-0.466 kJB.-7.94 kJC.-36.6 kJD.-68.4 kJE.-1.17 103 kJ

Q: Which of the following liquids has the largest enthalpy of vaporization? A.C5H12 B.C4H10 C.C3H8 D.C2H6 E.C6H14

Q: Equilibrium is established between a liquid and its vapor when A.the rate of evaporation equals the rate of condensation. B.equal masses exist in the liquid and gas phases. C.equal concentrations (in molarity) exist in the liquid and gas phases. D.all the liquid has evaporated. E.the liquid ceases to evaporate and the gas ceases to condense.

Q: Arrange Cl2, ICl, and Br2 in order from lowest to highest boiling point. A.Cl2 < Br2 < ICl B.Cl2 < ICl < Br2 C.ICl < Cl2 < Br2 D.Br2 < Cl2 < ICl E.Br2 < ICl < Cl2

Q: For which of the following pure solids is it necessary to break covalent bonds to make a liquid or gas: C(graphite), CO2(s), C60(s), and C(diamond)? A.C(graphite) only B.CO2(s) only C.CO2(s) and C60(s) D.C(graphite), C60(s) and C(diamond) E.C(graphite) and C(diamond)

Q: List all the intermolecular forces present in pure acetone. A.hydrogen bonding only B.dipole-dipole force only C.dipole-dipole force and induced dipole/induced dipole force D.hydrogen bonding and induced dipole/induced dipole force E.hydrogen bonding, dipole-dipole force, and induced dipole/induced dipole force

Q: What intermolecular force(s) is/are present in solid SO3? 1/ induced dipole/induced dipole 2/ dipole-dipole 3/ hydrogen bonding A.1 only B.2 only C.3 only D.1 and 2 E.1 and 3

Q: What intermolecular force or bond is primarily responsible for the solubility of CH3OH in water? A.ion-dipole force B.dipole-dipole force C.ionic bonding D.covalent bonding E.hydrogen bonding

Q: Which one of the following molecules has the lowest boiling point? A.CH4 B.CHCl3 C.CH2Cl2 D.CH3Cl E.CCl4

Q: A 0.175-L flask contains Cl2 at 25 C and 475 mm Hg. What is the pressure of the Cl2 if the volume is increased to 0.800 L and the temperature increased to 55 C? A.239 mm Hg B.94.4 mm Hg C.114 mm Hg D.241 mm Hg E.228 mm Hg

Q: A balloon is filled with He gas to a volume of 2.10 L at 35 C. The balloon is placed in liquid nitrogen until its temperature reaches -196 C. Assuming the pressure remains constant, what is the volume of the cooled balloon?A.-0.375 LB.0.375 LC.0.525 LD.0.00909 LE.8.40 L

Q: A tightly sealed 4.0-L flask contains 884 mm Hg of N2 at 94.0 C. The flask is cooled until the pressure is reduced 442 mm Hg. What is the temperature of the gas?A.-47.0 CB.47.0 CC.-89.5 CD.184 CE.188 C

Q: The lid is tightly sealed on a rigid flask containing 2.25 L Ar at 22 C and 0.977 atm. If the flask is heated to 102 C, what is the pressure in the flask? A.2.86 atm B.1.27 atm C.4.53 atm D.0.769 atm E.1.73 atm

Q: If the volume of a confined gas is expanded to four times the original volume while its temperature remains constant, what change will be observed? A.The pressure of the gas will decrease to 1/4 its original value. B.The pressure of the gas will decrease to 1/2 its original value. C.The pressure of the gas will remain unchanged. D.The pressure of the gas will increase to twice its original value. E.The pressure of the gas will increase to four times its original value.

Q: At constant temperature, 7.72 L of Cl2 at 458 mm Hg is compressed to 3.75 L. What is the final pressure of Cl2? A.0.485 mm Hg B.0.00106 mm Hg C.222 mm Hg D.943 mm Hg E.1820 mm Hg

Q: At 0.982 atm, the height of mercury in a barometer is 0.746 m. If the mercury were replaced with ethanol, what height of ethanol (in meters) would be supported at this pressure? The densities of Hg and ethanol are 13.5 g/cm3 and 0.789 g/cm3, respectively. A.0.0436 m B.0.946 m C.0.760 m D.12.8 m E.13.0 m

Q: Convert 618 mm Hg to kPa. (1 atm = 760 mm Hg = 101.3 kPa) A.0.0121 kPa B.1.23 kPa C.0.813 kPa D.82.4 kPa E.4.64 103 kPa

Q: Convert 0.449 bar to mm Hg. (1 atm = 760 mm Hg = 101.3 kPa = 1.013 bar)A.337 mm HgB.0.591 mm HgC.5.89 10-4 mm HgD.0.443 mm HgE.0.455 mm Hg

Q: What are two ways in which real gases differ from ideal gases?

Q: The pressure exerted by gas molecules inside a container is due to gas molecules colliding with the walls of the container. Why does one mole of oxygen molecules exert the same pressure inside a flask as one mole of hydrogen molecules, although the mass of an oxygen molecule is sixteen times greater than the mass of a hydrogen molecule?

Q: The ideal gas law can be modified to correct for the errors arising from nonideality. The modified equation is known as the ________ equation of state for a real gas.

Q: The gas constant, R, expressed in SI units has a value of 8.314. The units of the constant are ________.

Q: A statement of Avogadro's hypothesis is that equal volumes of gases under the same conditions of pressure and temperature will contain equal numbers of ________.

Q: Robert Boyle observed that the volume of a fixed amount of gas is inversely proportional to its ________.

Q: The rate of effusion of a gas is inversely proportional to the square root of its ________.

Q: A pressure of 1.00 atm has a metric equivalent of 1.01 105 ________.

Q: Which of the following statements concerning real gases is/are CORRECT? 1/ Real gases are always liquids or solids at temperatures below 273.15 K. 2/ The pressure of a real gas is higher than predicted by the ideal gas law. 3/ The molecules in a real gas are attracted to each other. A.1 only B.2 only C.3 only D.2 and 3 E.1, 2 and 3

Q: Non-ideal behavior for a gas is most likely to be observed under conditions of A.high temperature and low pressure. B.high temperature and high pressure. C.low temperature and low pressure. D.standard temperature and pressure. E.low temperature and high pressure.

Q: If a gas effuses 2.165 times faster than Xe, what is its molar mass? A.12.94 g/mol B.28.01 g/mol C.32.00 g/mol D.60.65 g/mol E.284.3 g/mol

Q: How long will it take 10.0 mL of Ne gas to effuse through a porous barrier if it has been observed that 125 minutes are required for 10.0 mL of Ar gas to effuse through the same barrier? A.1.41 min. B.31.9 min. C.63.1 min. D.88.8 min. E.176 min.

Q: Methane gas, CH4, effuses through a barrier at a rate of 0.568 mL/minute. If an unknown gas effuses through the same barrier at a rate of 0.343 mL/minute, what is the molar mass of the gas? A.20.8 g/mol B.28.0 g/mol C.32.0 g/mol D.44.0 g/mol E.64.0 g/mol

Q: The average velocity of a gas molecule is A.inversely proportional square root of its mass. B.inversely proportional to the gas constant, R. C.directly proportional to the square of its temperature in K. D.inversely proportional to its kinetic energy. E.directly proportional to the square of its temperature in C.

Q: Place the following gases in order of increasing average velocity at 300 K: Ar, CH4, N2, and N2O. A.Ar = CH4 = N2 = N2O B.N2O < Ar < N2 < CH4 C.N2O < N2 < CH4 < Ar D.Ar < N2 < N2O < CH4 E.CH4 < N2 < N2O < Ar

Q: What is the root-mean-square velocity of carbon dioxide molecules at 55 C? A.13.6 m/s B.42.8 m/s C.177 m/s D.186 m/s E.431 m/s

Q: Which of the following statements are postulates of the kinetic-molecular theory of gases? 1/ Gas particles are in constant, random motion. 2/ The distance between gas particles is large in comparison to their size. 3/ The average kinetic energy of gas particles is proportional to the kelvin temperature. A.1 only B.2 only C.3 only D.1 and 2 E.1, 2, and 3

Q: The layer of the atmosphere closest to the Earth's surface is the ________. A.thermosphere B.stratosphere C.stratopause D.troposphere E.mesosphere

Q: A 10.0 L flask at 318 K contains a mixture of Ar and CH4 with a total pressure of 1.040 atm. If the mole fraction of Ar is 0.715, what is the mass percent of Ar? A.13.8% B.68.8% C.71.5% D.82.9% E.86.2%

Q: A mixture of H2 and O2 is placed in a 5.00 L flask at 22 C. The partial pressure of the H2 is 2.7 atm and the partial pressure of the O2 is 1.5 atm. What is the mole fraction of H2? A.0.13 B.0.36 C.0.56 D.0.64 E.0.87

Q: Carbon monoxide reacts with oxygen to form carbon dioxide. 2 CO(g) + O2(g) 2 CO2(g) In a 1.00 L flask, 4.30 atm of CO reacts with 2.50 atm of O2. Assuming that the temperature remains constant, what is the final pressure in the flask? A.1.80 atm B.2.50 atm C.4.30 atm D.4.65 atm E.6.80 atm

Q: Water can be decomposed by electrolysis into hydrogen gas and oxygen gas. What mass of water must decompose to fill a 3.00 L flask to a total pressure of 2.00 atm at 298 K with a mixture hydrogen and oxygen? (R = 0.08206 Latm/molK) 2 H2O() 2 H2(g) + O2(g) A.1.47 g B.2.95 g C.4.42 g D.6.63 g E.8.84 g

Q: An unknown gaseous hydrocarbon contains 85.63% C. Its density is 1.524 g/L at 0.665 atm and 373 K. What is the molecular formula of the gas? (R = 0.08206 Latm/molK) A.C2H4 B.C3H6 C.C4H8 D.C5H10 E.C6H12

Q: When 0.5000 grams of an unknown hydrocarbon, CxHy, is completely combusted with excess oxygen, 1.037 L CO2 gas and is produced at 98.3 C and 1.000 atm. What is the empirical formula of the hydrocarbon? (R = 0.08206 Latm/molK) A.CH B.CH2 C.C2H3 D.C3H5 E.C3H8

Q: Aqueous hydrochloric acid reacts with magnesium to produce hydrogen gas according to the balanced equation below. 2 HCl(aq) + Mg(s) MgCl2(aq) + H2(g) If 250.0 mL of 3.00 M HCl is combined with 9.92 g Mg, what volume of hydrogen gas can be produced? Assume the temperature and pressure of the gas are 25 C and 0.988 atm, respectively. (R = 0.08206 Latm/molK) A.4.60 L B.5.05 L C.9.28 L D.10.1 L E.18.6 L

Q: Ammonia gas is synthesized according to the balanced equation below. N2(g) + 3 H2(g) 2 NH3(g) If 1.55 L N2 react with 4.92 L H2, what is the theoretical yield (in liters) of NH3? Assume that the volumes of reactants and products are measured at the same temperature and pressure. A.1.55 L B.3.10 L C.3.28 L D.4.93 L E.6.42 L

Q: If 6.46 L of gaseous ethanol reacts with 16.1 L O2, what is the maximum volume of gaseous carbon dioxde produced? Assume that the temperature of the reactants and products is 425 C and the pressure remains constant at 1.00 atm. CH3CH2OH(g) + 3 O2(g) 2 CO2(g) + 3 H2O(g) A.6.46 L B.10.7 L C.12.9 L D.16.1 L E.22.6 L

Q: Butane, C4H10, reacts with excess oxygen to produce carbon dioxide gas and water. What volume of CO2, measured at 25.0 C and 0.922 atm is produced from the reaction of 14.0 g C4H10 with excess oxygen? (R = 0.08206 Latm/molK) A.2.04 L B.3.72 L C.6.39 L D.8.15 L E.25.6 L

Q: What volume of O2, measured at 225 C and 0.970 atm, will be produced by the decomposition of 3.16 g KClO3? (R = 0.08206 Latm/molK) 2 KClO3(s) 2 KCl(s) + 3 O2(g) A.1.09 L B.1.24 L C.1.63 L D.3.26 L E.52.1 L

Q: What mass of O2 is required to produce 5.00 L NO2 at 305 K and 752 mm Hg? (R = 0.08206 Latm/molK) 2 NO(g) + O2(g) 2 NO2(g) A.0.198 g B.1.58 g C.3.16 g D.5.00 g E.6.33 g

Q: Sodium azide decomposes rapidly to produce nitrogen gas. 2 NaN3(s) 2 Na(s) + 3 N2(g) What mass of sodium azide will inflate a 60.0 L airbag for a car to a pressure of 1.50 atm at 32 C? (R = 0.08206 Latm/molK) A.2.40 g B.67.2 g C.156 g D.234 g E.351 g

Q: A mass of 1.37 g of an unknown gas is introduced into an evacuated 1.70 L flask. If the pressure in the flask is 0.814 atm at 98 C, which of the following gases might be in the flask? (R = 0.08206 Latm/molK) A.CH4 B.C2H2 C.C2H6 D.C3H8 E.C4H10

Q: At what temperature does 742 mm Hg of CH4 gas have the same density as 742 mm Hg of O2 gas at 273 K? A.137 K B.146 K C.191 K D.275 K E.545 K