A ) i o n i c B ) p o l a r c o v a l e n t C ) n o n p o l a r c o v a l e n t A n s : B C a t e g o r y : M e d i u m S e c t i o n : 9 . %- %, ] %- %, %, %, 9 G" %, - 6. The three compounds have essentially the same molar mass (5860 g/mol), so we must look at differences in polarity to predict the strength of the intermolecular dipoledipole interactions and thus the boiling points of the compounds. What fraction of the volume of each corner atom is actually within the volume of a face-centered cubic unit cell? Heat of sublimation can be approximated by adding together __________ and __________. B) ion-dipole forces. Bodies of water would freeze from the bottom up, which would be lethal for most aquatic creatures. KBr (1435C) > 2,4-dimethylheptane (132.9C) > CS2 (46.6C) > Cl2 (34.6C) > Ne (246C). Other factors must be considered to explain why many nonpolar molecules, such as bromine, benzene, and hexane, are liquids at room temperature; why others, such as iodine and naphthalene, are solids. %, %, %, ] B) polarizability. The three major types of intermolecular interactions are dipoledipole interactions, London dispersion forces (these two are often referred to collectively as van der Waals forces), and hydrogen bonds. B) trigonal pyramidal. The number of lone electron pairs in the NO2 ion is ___. Write a Lewis structure for OF2. 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. Pi bonds are covalent bonds in which the electron density is concentrated above and below a plane containing the nuclei of the bonding atoms. 1 8 J / g C DH v a p = 4 0 . The molecular property related to the ease with which the electron density in a neutral atom or molecule can be distorted is called A) a dipole moment. A) KI B) KBr C) KCl D) KF Ans:A Category:Medium Section:9.3 Chapter 10: (2 points each) 1. Larger atoms tend to be more polarizable than smaller ones, because their outer electrons are less tightly bound and are therefore more easily perturbed. On average, the two electrons in each He atom are uniformly distributed around the nucleus. Interactions between these temporary dipoles cause atoms to be attracted to one another. Liquids boil when the molecules have enough thermal energy to overcome the intermolecular attractive forces that hold them together, thereby forming bubbles of vapor within the liquid. A . Which of the following would be expected to have the lowest vapor pressure at room temperature? The Lewis dot symbol for the calcium ion is A) EMBED Equation.BREE42+ B) C a C ) E M B E D E q u a t i o n . B) covalent solid. Similarly, solids melt when the molecules acquire enough thermal energy to overcome the intermolecular forces that lock them into place in the solid. The Lewis dot symbol for the chloride ion is A) EMBED Equation.BREE4 B) EMBED Equation.BREE4 C) EMBED Equation.BREE4 D) EMBED Equation.BREE4 E) Cl Ans:B Category:Medium Section:9.2 11. b. Even the noble gases can be liquefied or solidified at low temperatures, high pressures, or both (Table \(\PageIndex{2}\)). Write the Lewis structure of boron trifluoride. C) polar bonds, and is a polar molecule. 11. dimethyl sulfoxide (boiling point = 189.9C) > ethyl methyl sulfide (boiling point = 67C) > 2-methylbutane (boiling point = 27.8C) > carbon tetrafluoride (boiling point = 128C). A ) I o n i c b o n d C ) P o l a r c o v a l e n t b o n d B ) N o n p o l a r c o v a l e n t b o n d D ) C o o r d i n a t e c o v a l e n t b o n d A n s : C C a t e g o r y : M e d i u m S e c t i o n : 9 . 1 9 . Of the following, __________ is the most volatile. The effect of this is that boiling points are lower at higher altitudes. 11.1: A Molecular Comparison of Gases, Liquids, and Solids, 2-methylpropane < ethyl methyl ether < acetone, Dipole Intermolecular Force, YouTube(opens in new window), Dispersion Intermolecular Force, YouTube(opens in new window), Hydrogen Bonding Intermolecular Force, YouTube(opens in new window), status page at https://status.libretexts.org. - Whether you need help solving quadratic equations, inspiration for the upcoming science fair or the latest update on a major storm, Sciencing is here to help. Consider a pair of adjacent He atoms, for example. . a. very weak compared with kinetic energies of the molecules a. London dispersion forces b. ion-dipole forces c. ionic bonding d. dipole-dipole forces C l a s s i f y t h e C C l b o n d i n C C l 4 a s i o n i c , p o l a r c o v a l e n t , o r n o n p o l a r c o v a l e n t . The ease of deformation of the electron distribution in an atom or molecule is called its polarizability. The overall order is thus as follows, with actual boiling points in parentheses: propane (42.1C) < 2-methylpropane (11.7C) < n-butane (0.5C) < n-pentane (36.1C). Use the graph of vapor pressure to determine the normal boiling point of O2. 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). Which one of the following molecules has tetrahedral geometry? a. Ionic b. Molecular c. Metallic C.A hydrogen bond can be thought of as a very strong dipole-dipole interaction. Which statement is true about liquids but not true about solids? Arrange C60 (buckminsterfullerene, which has a cage structure), NaCl, He, Ar, and N2O in order of increasing boiling points. They need more energy to escape to the gas phase, so the larger molecule has the higher boiling point. h|g CJ UVaJ "j h|g h|g B*EHUph je5(M A) ethanol, bp = 78C B) methanol, bp = 65C C) water, bp = 100C D) benzene, bp = 80C E) The vapor pressure of each of the liquids at its normal boiling point would be the same. The ease with which the charge distribution in a molecule can be distorted by an external electrical field is called the __________. The molecules within the liquid are attracted to each other. Br2. A) CH4 B) Cl2 C) Kr D) CH3Cl E) N2 Ans:D Category:Medium Section:11.2 7. Acetic acid and acetone are molecules based on two carbons. Intermolecular forces are generally much weaker than covalent bonds. At high altitudes, the atmospheric pressure is lower. Ans:D Category:Medium Section:11.3 15. h|g CJ UVaJ h>* B*ph h' h>* h>* B*OJ QJ ^J ph j h>* B*Uph "j h|g h|g B*EHUph H I ] ^ _ ` b B D F H L ` d yjXS h>* H*"j) h|g h|g B*EHUph jr5(M Of the following substances, ___ has the highest boiling point. The number of pi bonds in the molecule below is A) 1 B) 2 C) 3 D) 5 E) 9 Ans:C Category:Medium Section:10.5 26. According to VSEPR theory, which one of the following molecules should have a geometry that is trigonal bipyramidal? e. there is a higher moisture content in the air at high altitude, The pressure requires to liquefy a gas at its critical temperature, The temperature above which a gas cannot be liquified, On a phase diagram, the melting point is the same as the __________, When the phase diagram for a substance has a solid-liquid phase boundary line that has a negative slope (leans to the left), the substance __________. Ans: Category:Medium Section:9.6 43. A) Mg B) Ga C) Si D) Ba E) Pb Ans:C Category:Medium Section:9.5 20. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Of the following substances, only __________ has London dispersion forces as its only intermolecular force. A) Br2 B) Cl2 C) F2 D) I2 Ans:D Category:Easy Section:11.2 2. The boiling point of butane is close to 0 degrees Celsius, whereas the higher boiling point of butanone (79.6 degrees Celsius) can be explained by the shape of the molecule, which creates an attractive force between the oxygen on one molecule and the hydrogen on a neighboring molecule. 0 0 k g o f i r o n a t i t s m e l t i n g p o i n t ( 1 , 8 0 9 K ) , g i v e n t h a t DH f u s = 1 3 . A) Rb2O B) BaO C) SrO D) SeO2 E) MnO2 Ans:D Category:Easy Section:9.4 6. C l a s s i f y t h e C a C l b o n d i n C a C l 2 a s i o n i c , p o l a r c o v a l e n t , o r n o n p o l a r c o v a l e n t . Their structures are as follows: Asked for: order of increasing boiling points. Small nonpolar molecules 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. a) ion-ion attractions h|g h|g B*EHUph jo5(M Like covalent and ionic bonds, intermolecular interactions are the sum of both attractive and repulsive components. Ans: Category:Medium 42. h|g CJ UVaJ * , . N2 Br2 H2 Cl2 O2. 0 C t o s t e a m a t 1 0 0 C ? Intermolecular forces determine bulk properties, such as the melting points of solids and the boiling points of liquids. E) trigonal pyramidal. If they vibrate enough, they bump into each other. Doubling the distance (r 2r) decreases the attractive energy by one-half. 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. Write the Lewis structure of ammonia (nitrogen trihydride). 5 J A n s : C C a t e g o r y : M e d i u m S e c t i o n : 1 1 . 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 __________. A) H2O B) BF3 C) Cl2 D) SiH4 E) Ar. The number of atoms in a face-centered cubic unit cell is A) 1 B) 2 C) 3 D) 4 E) 8 Ans:D Category:Medium Section:11.4 19. C) the volume of the container. B) Water has an unusually high boiling point. 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. 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. (Despite this seemingly low value, the intermolecular forces in liquid water are among the strongest such forces known!) Butter melts over a range of temperature, rather than with a sharp melting point. Video Discussing Hydrogen Bonding Intermolecular Forces. Ans:E Category:Medium Section:11.8 12. 14 (mw=86) has a boiling point of 68. Which of the following substances should have the highest boiling point? d. Covalent-network e. Metallic and covalent-network, Crystalline solids __________. Ans: Category:Medium 41. C a l c u l a t e t h e a m o u n t o f h e a t n e e d e d t o m e l t 2 . B) vapor pressure is equal to, or greater than, the external pressure pushing on it. h|g CJ UVaJ ! " Which one of the following substances is expected to have the lowest melting point? Thus a substance such as \(\ce{HCl}\), which is partially held together by dipoledipole interactions, is a gas at room temperature and 1 atm pressure. Which of the following is not a type of solid? A) XeF4 B) BF3 C) AsF5 D) CF4 E) NH3 Ans:D Category:Medium Section:10.1 16. A) HCl B) AsCl5 C) ICl D) NCl3 E) Cl2 Ans:B Category:Medium Section:9.9 39. A) Se B) Sb C) K D) Ga E) Fe Ans:A Category:Medium Section:9.5 18. This is the expected trend in nonpolar molecules, for which London dispersion forces are the exclusive intermolecular forces. The predicted order is thus as follows, with actual boiling points in parentheses: He (269C) < Ar (185.7C) < N2O (88.5C) < C60 (>280C) < NaCl (1465C). (1) Na+ (2) CH3COOH (3) C2H6 (4) CH3NH2 A) (1) and (2) B) (1) and (3) C) (2) and (3) D) (2) and (4) E) (3) and (4) Ans:D Category:Medium Section:11.2 13. All molecules, whether polar or nonpolar, are attracted to one another by London dispersion forces in addition to any other attractive forces that may be present. The force of attraction that exists between Na+ and H2O is called a(n) __________ interaction. 0 f. %, 2 Y) r 2 %, 2 %, ] ] %, ] ] ] ] ] K- K- * Z ] ] ] f. ] ] ] ] 2 ] ] ] ] ] ] ] ] ] | : Chapter 9: (2 points each) 1. 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. 8 k J D ) 4 0 . Video Discussing Dipole Intermolecular Forces. Draw the hydrogen-bonded structures. Small polar molecules 5 2 1 . Which of the following pairs of elements would be most likely to form an ionic compound? E) The vapor pressure of each of the liquids at its normal boiling point would be the same. Calculate the moment of inertia, radius of gyration, and the polar moment of inertia about the centroid. A molecule with a double-bonded oxygen, like butanone (C4H8O) is peaked in the middle where the oxygen is bonded to the carbon chain. What is the major attractive force that exists among different I2 molecules in the solid? A) S B) O C) F D) N Ans:A Category:Easy Section:11.2 14. Ans: Category:Medium Section:9.6 47. Use VSEPR theory to predict the geometry of the PCl3 molecule. Indicate all the types of intermolecular forces of attraction in C2H6(g). Intermolecular forces are electrostatic in nature; that is, they arise from the interaction between positively and negatively charged species. Which of the responses includes all of the following that can form hydrogen bonds with water molecules? Vaporization and more. e. readily evaporates, V olatility and vapor pressure are __________. C) trigonal planar. Recall that the attractive energy between two ions is proportional to 1/r, where r is the distance between the ions. E) ionic crystal. In larger atoms such as Xe, however, the outer electrons are much less strongly attracted to the nucleus because of filled intervening shells. In which of the following molecules is hydrogen bonding likely to be the most significant component of the total intermolecular forces? According to the VSEPR theory, the molecular geometry of beryllium chloride is A) linear B) trigonal planar C) bent D) tetrahedral E) trigonal pyramidal Ans:A Category:Medium Section:10.1 9. b. heat of fusion, heat of vaporization Which of the following substances will display an incomplete octet in its Lewis structure? a. h|g CJ UVaJ h>* B*ph h>* j h>* B*Uph "j h|g h|g B*EHUph jh5(M The effect is most dramatic for water: if we extend the straight line connecting the points for H2Te and H2Se to the line for period 2, we obtain an estimated boiling point of 130C for water! Identify the most significant intermolecular force in each substance. b. a long range repeating pattern of atoms, molecules, or ions, The unit cell with all sides the same length and all angles equal to 90 that has lattice points only at the corners is called __________. The substance with the weakest forces will have the lowest boiling point. Chemistry Dashboard - Ammonia: How Can You Determine If a Molecule Has a Higher Boiling Point, 10842 Rubidium nitrate: How Can You Determine If a Molecule Has a Higher Boiling Point, the presence of a longer chain of atoms in the molecule (more polarizable), functional groups that are more exposed (that is, at the end of a chain, rather than in the middle), the polarity ranking of functional groups: Amide>Acid>Alcohol>Ketone or Aldehyde>Amine>Ester>Alkane. 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. S, 3. Which one of the following is most likely to be a covalent compound? According to the VSEPR theory, which one of the following species should be linear? The acetone has a double-bonded oxygen in the middle, rather than at the end, which creates weaker interactions between molecules. D) bent. The most significant intermolecular force for this substance would be dispersion forces. B) trigonal planar. Of the following substances, _____ has the highest boiling point. h|g CJ UVaJ h>* B*OJ QJ ^J ph h>* H*h>* B*H*ph "j A) CaCl2 B) CO2 C) CS2 D) SO2 E) OF2 Ans:A Category:Easy Section:9.2 2. Ans:E Category:Medium Section:10.1 6. Instantaneous dipoleinduced dipole interactions between nonpolar molecules can produce intermolecular attractions just as they produce interatomic attractions in monatomic substances like Xe. Which response includes all the molecules below that do not follow the octet rule? Of the given pair of compounds, which would have the higher boiling point? T h e L e w i s d o t s y m b o l f o r t h e S 2 i o n i s A ) E M B E D E q u a t i o n . Consequently, we expect intermolecular interactions for n-butane to be stronger due to its larger surface area, resulting in a higher boiling point. a. e. strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other, As a solid element melts, the atoms become _____ and they have _____ attraction for each other, Together, liquids and solids constitute ________ phases of matter. Which of the following is not an endothermic process? Molecules should have the lowest melting point value, the external pressure pushing on it Fe:. Is called the __________ points are lower at higher altitudes with the weakest forces will the... Than at the end, which one of the following pairs of elements would be the same and! 2R ) decreases the attractive energy between two ions is proportional to 1/r, where is. To VSEPR theory, which would be the same attractive energy between ions. 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which substance most likely has the highest boiling point quizlet