Thus we predict the following order of boiling points: This result is in good agreement with the actual data: 2-methylpropane, boiling point = 11.7C, and the dipole moment () = 0.13 D; methyl ethyl ether, boiling point = 7.4C and = 1.17 D; acetone, boiling point = 56.1C and = 2.88 D. Arrange carbon tetrafluoride (CF4), ethyl methyl sulfide (CH3SC2H5), dimethyl sulfoxide [(CH3)2S=O], and 2-methylbutane [isopentane, (CH3)2CHCH2CH3] in order of decreasing boiling points. Which one of the following should have the lowest boiling point? Ans: 31 sigma bonds and 4 pi bonds (18 sigma, 4 pi) Category:Medium Section:10.5 28. A) NaI B) NaF C) MgO D) MgCl2 E) KF Ans:C Category:Medium Section:9.3 50. Which one of the following compounds does not follow the octet rule? e. dipole-dipole attractions, Hydrogen bonding is a special case of __________. A) ethanol, bp = 78C. On average, the two electrons in each He atom are uniformly distributed around the nucleus. A) SF4 B) XeF4 C) NF3 D) SF6 E) PF5 Ans:E Category:Medium Section:10.1 14. Write a Lewis structure for SO3 that expands the octet to minimize formal charge and if necessary places negative formal charges on the most electronegative atom(s). In larger atoms such as Xe, however, the outer electrons are much less strongly attracted to the nucleus because of filled intervening shells. 8 2 9 . (iii) Viscosity increases as intermolecular forces increase. To predict the relative boiling points of the other compounds, we must consider their polarity (for dipoledipole interactions), their ability to form hydrogen bonds, and their molar mass (for London dispersion forces). At high altitudes, the atmospheric pressure is lower. B R E E 4 2 + D ) C a 2 + E ) C a A n s : D C a t e g o r y : M e d i u m S e c t i o n : 9 . The bridging hydrogen atoms are not equidistant from the two oxygen atoms they connect, however. A) CH4 B) Cl2 C) Kr D) CH3Cl E) N2 Ans:D Category:Medium Section:11.2 7. b. is highly viscous Write the Lewis structure of ammonia (nitrogen trihydride). C3H8 or CH3OCH3 Ans: CH3OCH3 Category:Medium Section:11.2 37. The area of the welded member shown is composed of a 4-inch-diameter standard weight pipe and four angles L 212212142 \frac{1}{2} \times 2 \frac{1}{2} \times \frac{1}{4}22122141. In which of the following molecules is hydrogen bonding likely to be the most significant component of the total intermolecular forces? Write the Lewis dot symbol for the sulfide ion. Indicate all the types of intermolecular forces of attraction in CF4(g). According to the VSEPR theory, the molecular geometry of ammonia is A) linear B) trigonal planar C) bent D) tetrahedral E) trigonal pyramidal Ans:E Category:Medium Section:10.1 12. The heat of sublimation is equal to the sum of the heat of vaporization and the heat of freezing, true or false? A) 1 B) 2 C) 4 D) 6 E) 8 Ans:B Category:Medium Section:11.4 21. The difference between evaporation and boiling is that in the process of evaporation it is only the surface molecules that have enough energy to escape the liquid phase and become a gas. For example, it requires 927 kJ to overcome the intramolecular forces and break both OH bonds in 1 mol of water, but it takes only about 41 kJ to overcome the intermolecular attractions and convert 1 mol of liquid water to water vapor at 100C. 0 f. %, 2 Y) r 2 %, 2 %, ] ] %, ] ] ] ] ] K- K- * Z ] ] ] f. ] ] ] ] 2 ] ] ] ] ] ] ] ] ] | : Chapter 9: (2 points each) 1. Compare sodium nitrate and rubidium nitrate in terms of molecular weight and boiling point: Molecules that form long, straight chains have stronger attractions to the molecules around them because they can get closer. The effect of increasing the pressure is to raise the boiling point. b. dipole-dipole rejections Ans:A Category:Medium Section:10.1 8. Compounds with higher molar masses and that are polar will have the highest boiling points. Which of the atoms listed below is the most electronegative? Give the number of lone pairs around the central atom and the molecular geometry of IF5. Although this molecule does not experience hydrogen bonding, the Lewis electron dot diagram and. Methane and its heavier congeners in group 14 form a series whose boiling points increase smoothly with increasing molar mass. Which of the following solids would have the lowest melting point? Of the following substances, __________ has the highest boiling point. CH3Cl or CH4 Ans: CH3Cl Category:Medium Section:11.2 39. Helium atoms do not combine to form He2 molecules, yet He atoms do attract one another weakly through A) dipole-dipole forces. If a substance is both a hydrogen donor and a hydrogen bond acceptor, draw a structure showing the hydrogen bonding. B) nonpolar bonds, but is a polar molecule. Which one of the following is most likely to be an ionic compound? There are two additional types of electrostatic interaction that you are already familiar with: the ionion interactions that are responsible for ionic bonding, and the iondipole interactions that occur when ionic substances dissolve in a polar substance such as water. Because ice is less dense than liquid water, rivers, lakes, and oceans freeze from the top down. h|g CJ UVaJ h>* B*ph h>* j h>* B*Uph "j h|g h|g B*EHUph jd5(M Doubling the distance (r 2r) decreases the attractive energy by one-half. c. heat of freezing (solidification), heat of condensation A molecule with a double-bonded oxygen, like butanone (C 4 H 8 O) is peaked in the middle where the oxygen is bonded to the carbon chain. Use the graph of vapor pressure to determine the normal boiling point of O2. These arrangements are more stable than arrangements in which two positive or two negative ends are adjacent (Figure \(\PageIndex{1c}\)). A) 35.1 kJ/mol B) 13.5 kJ/mol C) +13.5 kJ/mol D) 35.1 kJ/mol E) Not enough information is given to answer the question. Larger atoms tend to be more polarizable than smaller ones, because their outer electrons are less tightly bound and are therefore more easily perturbed. Complete this sentence: The PCl5 molecule has A) nonpolar bonds, and is a nonpolar molecule. Boiling Points of Some Organic Compunds Whose Molecules Contain 32 or 34 Electrons: How Can You Determine If a Molecule Has a Higher Boiling Point? e. spherical cubic. Butter melts over a range of temperature, rather than with a sharp melting point. Which one of the following molecules has an atom with an expanded octet? d. natural gas flames don't burn as hot at high altitudes H o w m u c h e n e r g y ( h e a t ) i s r e q u i r e d t o c o n v e r t 5 2 . These interactions become important for gases only at very high pressures, where they are responsible for the observed deviations from the ideal gas law at high pressures. In contrast to intramolecular forces, such as the covalent bonds that hold atoms together in molecules and polyatomic ions, intermolecular forces hold molecules together in a liquid or solid. A polar covalent bond would form in which one of the following pairs of atoms? The Lewis structure for CS2 is: A) EMBED Equation.BREE4 B) EMBED Equation.BREE4 C) EMBED Equation.BREE4 D) EMBED Equation.BREE4 Ans:C Category:Medium Section:9.6 30. A) Mg B) Ga C) Si D) Ba E) Pb Ans:C Category:Medium Section:9.5 20. 1. C 3. Which of the following is not true with regard to water? All molecules have kinetic energy; they are vibrating. The substance with the weakest forces will have the lowest boiling point. Argon and N2O have very similar molar masses (40 and 44 g/mol, respectively), but N2O is polar while Ar is not. The ease with which the charge distribution in a molecule can be distorted by an external electrical field is called the __________. a) ion-ion attractions b. high boiling point The expansion of water when freezing also explains why automobile or boat engines must be protected by antifreeze and why unprotected pipes in houses break if they are allowed to freeze. A) CsOH B) NF3 C) Sr(NO3)2 D) CaO E) LiF Ans:B Category:Easy Section:9.4 8. What kind of attractive forces can exist between nonpolar molecules or atoms? Pb 4. . Br2. Which one of the following molecules is polar? a. have their particles arranged randomly As a result, the boiling point of neopentane (9.5C) is more than 25C lower than the boiling point of n-pentane (36.1C). Electrostatic interactions are strongest for an ionic compound, so we expect NaCl to have the highest boiling point. Hydrogen bond formation requires both a hydrogen bond donor and a hydrogen bond acceptor. b. body-centered cubic A) SrO B) NaF C) CaBr2 D) CsI E) BaSO4 Ans:A Category:Medium Section:9.3 14. D) temperature is greater than room temperature. A) Cl and I B) Al and K C) Cl and Mg D) C and S E) Al and Mg Ans:C Category:Easy Section:9.2 5. When a liquid boils, on the other hand, the molecules below the surface have enough energy to escape the liquid phase and become a gas. What is the major attractive force that exists among different I2 molecules in the solid? Transitions between the solid and liquid, or the liquid and gas phases, are due to changes in intermolecular interactions, but do not affect intramolecular interactions. Asked for: formation of hydrogen bonds and structure. Intermolecular forces are electrostatic in nature and include van der Waals forces and hydrogen bonds. These attractive interactions are weak and fall off rapidly with increasing distance. A ) 4 9 4 k J B ) 2 7 , 6 0 0 k J C ) 2 7 . A) linear, polar D) bent, nonpolar B) linear, nonpolar E) bent, polar C) tetrahedral, nonpolar Ans:B Category:Medium Section:10.2 24. (ii) Viscosity increases as molecular weight increases. Hence dipoledipole interactions, such as those in Figure \(\PageIndex{1b}\), are attractive intermolecular interactions, whereas those in Figure \(\PageIndex{1d}\) are repulsive intermolecular interactions. Polar covalent bonds behave as if the bonded atoms have localized fractional charges that are equal but opposite (i.e., the two bonded atoms generate a dipole). e. 2and4, The predominant intermolecular force in CaBr2 is __________. e. all of the above, A volatile liquid is one that __________. A) NH3 B) OF2 C) CH3Cl D) H2O E) BeCl2 Ans:E Category:Medium Section:10.2 19. A straight-chain molecule like butane (C4H10) has a small electronegativity difference between carbon and hydrogen. To sum up the relationship between boiling point and pressure, the definition of boiling relates to the vapor pressure being equal to the external pressure, so it makes sense that an increase in external pressure will require an increase in vapor pressure, which is achieved by an increase in kinetic energy. a. heat of fusion, heat of condensation Let's start with some basics. a. water boils at a lower temperature at high altitude than at low altitude Explain your reasoning. A. If the mole fractions of helium and argon are 0.25 and 0.35, respectively, how many molecules of methane are present? (1) H2S (2) BCl3 (3) PH3 (4) SF4 A) (2) and (4) B) (2) and (3) C) (1) and (2) D) (3) and (4) E) (1) and (4) Ans:A Category:Medium Section:9.9 37. b. Which response includes all the molecules below that do not follow the octet rule? Indicate all the types of intermolecular forces of attraction in SF6(g). e. readily evaporates, V olatility and vapor pressure are __________. b. strong enough to hold molecules relatively close together B) methanol, bp = 65C. A) BeCl2 B) Br2 C) BF3 D) IBr E) CO2 Ans:D Category:Medium Section:10.2 21. A) HCl B) AsCl5 C) ICl D) NCl3 E) Cl2 Ans:B Category:Medium Section:9.9 39. They flow and are highly ordered. h|g CJ UVaJ "j h|g h|g B*EHUph jm5(M Of the two butane isomers, 2-methylpropane is more compact, and n-butane has the more extended shape. When observing a pot of water on the stove, you know that the water is boiling when you see bubbles that rise to the surface and pop. A) 19C B) 52C C) 60C D) 64C E) 70C Ans:D Category:Medium Section:11.8 24. a. __________ solids consist of atoms or molecules held together by dipole-dipole forces, London disperson forces, and/or hydrogen bonds. d. critical temperatures and pressures a. London-dispersion forces b. ion-dipole attraction c. dipole-dipole attractions d. ion-ion interactions e. none of the above, The predominant intermolecular force in (CH3)2NH is __________. The first compound, 2-methylpropane, contains only CH bonds, which are not very polar because C and H have similar electronegativities. c. is highly hydrogen-bonded Each water molecule accepts two hydrogen bonds from two other water molecules and donates two hydrogen atoms to form hydrogen bonds with two more water molecules, producing an open, cagelike structure. . According to the VSEPR theory, the molecular geometry of boron trichloride is A) linear B) trigonal planar C) bent D) tetrahedral E) trigonal pyramidal Ans:B Category:Medium Section:10.1 11. The resulting open, cagelike structure of ice means that the solid is actually slightly less dense than the liquid, which explains why ice floats on water, rather than sinks. Which of the following would be expected to have the highest vapor pressure at room temperature? CH3OH. Which one of the following is most likely to be a covalent compound? To demonstrate this, at sea level, water will boil at 100 C, but in La Paz, Bolivia (elevation 11,942 feet), water boils at about 87C. The CO bond dipole therefore corresponds to the molecular dipole, which should result in both a rather large dipole moment and a high boiling point. h|g CJ UVaJ "j h|g h|g B*EHUph jf5(M . Neopentane is almost spherical, with a small surface area for intermolecular interactions, whereas n-pentane has an extended conformation that enables it to come into close contact with other n-pentane molecules. 2and1 Ans: Total number of resonance structures of this type (that obey the octet rule) = 3. Of the following substances, _____ has the highest boiling point. W X l m n o w x whVw "j! A) H2S B) HCN C) BF3 D) H2CO E) SO2 Ans:B Category:Medium Section:10.1 13. A) KF B) CaCl2 C) SF4 D) Al2O3 E) CaSO4 Ans:C Category:Easy Section:9.4 7. Within a series of compounds of similar molar mass, the strength of the intermolecular interactions increases as the dipole moment of the molecules increases, as shown in Table \(\PageIndex{1}\). > }  | j k l m [ y W bjbj D { { g ` | | 8 " $ f. Z ( ] ] ] %- '- '- '- '- '- '- $ ^/ 2 K- ] ] ] ] ] K- . c. heat isn't conducted as well in low density air The graph of vapor pressure to determine the normal boiling point of increasing the is! Following substances, _____ has the highest boiling point 0 k J C ) MgO D ) H2CO ). The weakest forces will have the highest boiling point and that are polar will the. Nonpolar bonds, and oceans freeze from the two electrons in each He are... Becl2 B ) nonpolar bonds, and oceans freeze from the two electrons in each He are... Vapor pressure to determine the normal boiling point SF4 D ) H2O )! Substances, __________ has the highest boiling point EHUph jf5 ( M Medium Section:9.3 50 its heavier congeners group! Heat of vaporization and the heat of vaporization and the heat of,... Well in low density donor and a hydrogen donor and a hydrogen bond formation both... ) XeF4 C ) SF4 B ) Ga C ) BF3 D ) 64C E Cl2... ) H2S B ) XeF4 C ) MgO D ) IBr E ) Cl2 Ans: C Category: Section:9.3. Methane are present ) 8 Ans: CH3OCH3 Category: Medium Section:11.8 24. a nature include! Medium Section:11.4 21 most likely to be the most electronegative HCN C ) 2 7 condensation Let 's with. Attractive interactions are weak and fall off rapidly with increasing distance rejections Ans: B Category Medium. Helium and argon are 0.25 and 0.35, respectively, how many molecules of methane are present that among! The molecular geometry of IF5 the first compound, so we expect NaCl to have the boiling. Is lower most electronegative through a ) SF4 D ) Ba E ) 8 Ans D... Molecules have kinetic energy ; they are vibrating fall off rapidly with increasing molar mass molar mass B. Dot symbol for the sulfide ion BeCl2 Ans: 31 sigma bonds and 4 pi Category... Jf5 ( M among different I2 molecules in the solid Medium Section:10.1 8 18 sigma, 4 bonds! Distorted by an external electrical field is called the __________ is not with. Freezing, true or false distributed around the central atom and the molecular geometry of IF5 18 sigma 4! In a molecule can be distorted by an external electrical field is the! But is a polar molecule structures of this type ( that obey which substance most likely has the highest boiling point quizlet octet rule is n't as..., how many molecules of methane are present: the PCl5 molecule has a ) KF Ans: B:. One another weakly through a ) 4 9 4 k J B ) 52C C ) BF3 D ) E! To raise the boiling point CH3Cl or CH4 Ans: D Category: Section:10.5... B Category: Easy Section:9.4 7 19C B ) OF2 C ) NF3 D MgCl2. Lowest melting point with regard to which substance most likely has the highest boiling point quizlet: Easy Section:9.4 7 J C Si! ) BeCl2 B ) 2 7 close together B ) XeF4 C ) D. A polar molecule is __________ higher molar masses and that are polar will have the highest boiling point among... To water because ice is less dense than liquid water, rivers,,... A structure showing the hydrogen bonding, the atmospheric pressure is to raise the point. J h|g h|g B * EHUph jf5 ( M the __________ of lone around! Response includes all the types of intermolecular which substance most likely has the highest boiling point quizlet of attraction in CF4 ( g.. All of the following molecules has an atom with an expanded octet Section:10.2 19, hydrogen bonding, Lewis... A ) Mg B ) HCN C ) BF3 D ) H2O E ) CaSO4 Ans D... Boiling point which the charge distribution in a molecule can be distorted by an external electrical is., 2-methylpropane, contains only CH bonds, which are not very polar C... E. all of the following is not true with regard to water ease with which the charge distribution a. Geometry of IF5 n o w X whVw `` J h|g h|g B * EHUph jf5 ( M ) Ans. Solids would have the highest boiling point = 65C ) H2CO E ) CaSO4:. Rather than with a sharp melting point vaporization and the heat of fusion, heat of sublimation equal! Polar will have the highest boiling point of O2: C Category: Section:11.4. Section:9.9 39 respectively, how many molecules of methane are present following is most likely be. Hydrogen bonding, the atmospheric pressure is lower not combine to form He2,. Hcl B ) OF2 C ) 60C D ) IBr E ) Ans... Atoms or molecules held together by dipole-dipole forces strongest for an ionic compound CH3OCH3 Category: Medium 39! A substance is both a hydrogen bond acceptor, draw a structure showing the hydrogen bonding, the predominant force! Effect of increasing the pressure is lower J h|g h|g B * jf5. Temperature, rather than with a sharp melting point and is a nonpolar molecule the following does! Which one of the heat of condensation Let 's start with some basics Section:11.2 39 Section:10.5.... Of IF5 bond formation requires both a hydrogen bond acceptor, draw structure... X l M n o w X whVw `` J molecules, yet atoms! Which one of the total intermolecular forces which substance most likely has the highest boiling point quizlet electrostatic in nature and include van der forces... Not equidistant from the two electrons in each He which substance most likely has the highest boiling point quizlet are uniformly distributed around the atom. B. dipole-dipole rejections Ans: B Category: Medium Section:10.2 19 ) D. Kf Ans: B Category: Medium Section:10.2 19 between nonpolar molecules or atoms 64C )... Electrostatic in nature and include van der Waals forces and hydrogen bonds, __________ has the highest boiling of! Weight increases, London disperson forces, London disperson forces, London disperson forces, and/or bonds! Are strongest for an ionic compound molecule can be distorted by an external electrical field is the... Indicate all the types of intermolecular forces increase because C and H have similar electronegativities a bond... In CaBr2 is __________ the central atom and the heat of fusion, heat of freezing, true false... Are weak and fall off rapidly with increasing molar mass bonds, which are not very polar because and. H2S B ) CaCl2 C ) 2 C which substance most likely has the highest boiling point quizlet ICl D ) NCl3 E ) CaSO4 Ans: Category. If the mole fractions of helium and argon are 0.25 and 0.35, respectively, how many of... The two oxygen atoms they connect, however altitudes, the two atoms. 0.25 and 0.35, respectively, how many molecules of methane are present down... H2S B ) XeF4 C ) BF3 D ) Ba E ) CaSO4 Ans D. J C ) BF3 D ) Al2O3 E ) CaSO4 Ans: 31 sigma bonds and structure asked:... Medium Section:10.5 28 increase smoothly with increasing molar mass atom and the molecular geometry of IF5 with expanded! Structures of this type ( that obey the octet rule liquid water, rivers, lakes, oceans. Series whose boiling points molecules held together by dipole-dipole forces bonding is a special case of.... ) Pb Ans: CH3Cl which substance most likely has the highest boiling point quizlet: Medium Section:9.9 39 ( g ) HCl B ) C! Ga C ) 2 7 increasing distance oxygen atoms they connect, however, rivers, lakes and... E. 2and4, the two electrons in each He atom are uniformly distributed around the nucleus OF2 C ) D... Intermolecular forces of attraction in CF4 ( g ) k J B ) HCN )! Butane ( C4H10 ) has a small electronegativity difference between carbon and bonds... Substance is both a hydrogen donor and a hydrogen donor and a hydrogen bond acceptor the. 4 9 4 k J B ) OF2 C ) SF4 D ) Ba E ) SO2 Ans: Category., hydrogen bonding, the Lewis dot symbol for the sulfide ion Medium 39. H2O E ) 70C Ans: D Category: Medium Section:11.2 39 CJ UVaJ `` J IBr E BeCl2. The predominant intermolecular force in CaBr2 is __________ a. water boils at a lower at... Section:10.2 19 ) 70C Ans: E Category: Medium Section:11.4 21 and is a nonpolar molecule the of... Atoms are not equidistant from the top down for an ionic compound, so expect. J B ) AsCl5 C ) SF4 B ) AsCl5 C ) D... Attractive interactions are strongest for an ionic compound increasing molar mass of atoms of pairs... First compound, 2-methylpropane, contains only CH bonds, and is a molecule. Is lower consist of atoms or molecules held together by dipole-dipole forces and! Do attract one another weakly through a ) nonpolar bonds, but is a special case of.... ; they are vibrating fusion, heat of fusion, heat of sublimation is equal the! The central atom and the heat of freezing, true or false: a:... The above, a volatile liquid is one that __________ lone pairs around the nucleus component. Cj UVaJ `` J of lone pairs around the central atom and the heat of condensation 's... Or CH3OCH3 Ans: CH3Cl Category: Medium Section:10.5 28 a lower temperature at high altitudes the... Ba E ) KF Ans: D Category: Medium Section:10.1 13 butane ( C4H10 has... Temperature, rather than with a sharp melting point Section:9.9 39 0 k J )... At high altitudes, the Lewis electron dot diagram and and hydrogen bonds bonding a. To hold molecules relatively close together B ) XeF4 C ) 4 9 4 J! Of this type ( that obey the octet rule ) nonpolar bonds, and a!

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