The molar heat of fusion of benzene is 9.92 kJ/mol. Its molar heat of vaporization is 30.7 kJ/mol. Calculate the heat required to melt 8.25 g of benzene at its normal melting point. Calculate the heat required to vaporize 8.25 g of benzene at its normal boiling point. Why is the heat of vaporization more than three times the heat of fusion?
> At what temperature would 4.25 g of oxygen gas, O2, exert a pressure of 784 mm Hg in a 2.51-L container?
> At what temperature will a 1.0-g sample of neon gas exert a pressure of 500. torr in a 5.0-L container?
> Write the simple Lewis structure for each of the following atoms. a. Mg (Z = 12) b. Br (Z = 35) c. S (Z = 16) d. Si (Z = 14)
> Write the simple Lewis structure for each of the following atoms. a. I (Z = 53) b. Al (Z = 13) c. Xe (Z = 54) d. Sr (Z = 38)
> What does it mean when two atoms in a molecule are connected by a “triple bond”? Write the Lewis structure of a molecule containing a triple bond.
> What does it mean when we say that in forming bonds, atoms try to achieve an electron configuration analogous to a noble gas?
> How many electrons are involved when two atoms in a molecule are connected by a “double bond”? Write the Lewis structure of a molecule containing a double bond.
> When elements in the second and third periods occur in compounds, what number of electrons in the valence shell represents the most stable electron arrangement? Why?
> What type of structure must each atom in a compound usually exhibit for the compound to be stable?
> The volume of a sample of ideal gas is proportional to its temperature (K) at constant pressure.
> Why are the valence electrons of an atom the only electrons likely to be involved in bonding to other atoms?
> Figures 13.7 and 13.8 show volume/temperature data for several samples of gases. Why do all the lines seem to extrapolate to the same point at 2273 °C? Explain. High temperature Large volume Low temperature Small volume He He 5 CH, CH, H,
> Pretend that you’re talking to a friend who has not yet taken any science courses, and describe how you would explain the concept of absolute zero to him.
> Under what conditions do real gases behave most ideally?
> What pressure (in atmospheres) is required to compress 1.00 L of gas at 760. mm Hg pressure to a volume of 50.0 mL?
> Why are anions always larger than the atoms from which they are formed?
> The normal boiling point of water is unusually high, compared to the boiling points of H2S, H2Se, and H2Te. Explain this observation in terms of the hydrogen bonding that exists in water, but that does not exist in the other compounds.
> Why are cations always smaller than the atoms from which they are formed?
> If 1.04 g of chlorine gas occupies a volume of 872 mL at a particular temperature and pressure, what volume will 2.08 g of chlorine gas occupy under the same conditions?
> Is the formula we write for an ionic compound the molecular formula or the empirical formula? Why?
> Atoms form ions so as to achieve electron configurations similar to those of the noble gases. For the following pairs of noble gas configurations, give the formulas of two simple ionic compounds that would have comparable electron configurations. a. [He
> Name the noble gas atom that has the same electron configuration as each of the ions in the following compounds. a. barium sulfide, BaS b. strontium fluoride, SrF2 c. magnesium oxide, MgO d. aluminum sulfide, Al2S3
> A sample of gas has a volume of 127 mL in a boiling water bath at 100 °C. Calculate the volume of the sample of gas at 10 °C intervals after the heat source is turned off and the gas sample begins to cool down to the temperature of the laboratory, 20 °C.
> If a 375-mL sample of neon gas is heated from 24 °C to 72 °C at constant pressure, what will be the volume of the sample at the higher temperature?
> What is the expected ground-state electron configuration for Te-2?
> For each of the following numbers of electrons, give the formula of a positive ion that would have that number of electrons, and write the complete electron configuration for each ion. a. 10 electrons b. 2 electrons c. 18 electrons d. 36 electrons
> Which simple ion would each of the following elements be expected to form? Which noble gas has an analogous electron configuration to each of the ions? a. bromine, Z = 35 b. cesium, Z = 55 c. phosphorus, Z = 15 d. sulfur, Z = 16
> The boiling points of the noble gas elements are listed below. Comment on the trend in the boiling points. Why do the boiling points vary in this manner? Не - 272 °С Kr -152.3 °С Ne -245.9 °С Хе —107.1 °С Ar -185.7°С Rn -61.8 °C
> A sample of helium gas with a volume of 29.2 mL at 785 mm Hg is compressed at constant temperature until its volume is 15.1 mL. What will be the new pressure in the sample?
> If the pressure on a 1.04-L sample of gas is doubled at constant temperature, what will be the new volume of the gas?
> Nonmetals form negative ions by (losing/gaining) enough electrons to achieve the electron configuration of the next noble gas.
> The metallic elements lose electrons when reacting, and the resulting positive ions have an electron configuration analogous to the noble gas element.
> A sample of gas in a balloon has an initial temperature of 18 °C and a volume of 1340 L. If the temperature changes to 87 °C and there is no overall change of pressure or amount of gas, what is the new volume of the gas?
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. H-C b. N-O c. N-S d. N-C
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. Si-H b. P-H c. S-H d. Cl-H
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. S-P b. S-F c. S-Cl d. S-Br
> For each of the following bonds, draw a figure indicating the direction of the bond dipole, including which end of the bond is positive and which is negative. a. C-F b. Si-C c. C-O d. B-C
> In each of the following diatomic molecules, which end of the molecule is positive relative to the other end? a. hydrogen fluoride, HF b. chlorine monofluoride, ClF c. iodine monochloride, ICl
> The molar heats of fusion and vaporization for water are 6.02 kJ/mol and 40.6 kJ/mol, respectively, and the specific heat capacity of liquid water is 4.18 J/g °C. What quantity of heat energy is required to melt 25.0 g of ice at 0 °C? What quantity of he
> In each of the following diatomic molecules, which end of the molecule is negative relative to the other end? a. hydrogen chloride, HCl b. carbon monoxide, CO c. bromine monofluoride, BrF
> Why is the presence of a dipole moment in the water molecule so important? What are some properties of water that are determined by its polarity?
> What volume of gas would result if 225 mL of neon gas is compressed from 1.02 atm to 2.99 atm at constant temperature?
> Which bond in each of the following pairs has less ionic character? a. Na-O or Na-N b. K-S or K-P c. Na-Cl or K-Cl d. Na-Cl or Mg-Cl
> In Fig. 13.4, when additional mercury is added to the righthand arm of the J-shaped tube, the volume of the gas trapped above the mercury in the left-hand arm of the J-tube decreases. Explain. Mercury added Gas Gas h Hg Figure 13.4 A J-tube similar
> Pretend that you’re talking to a friend who has not yet taken any science courses, and describe how you would explain Boyle’s law to her.
> Make the indicated pressure conversions. a. 17.3 psi to kilopascals b. 1.15 atm to psi c. 4.25 atm to mm Hg d. 224 psi to atmospheres
> A mathematical expression that summarizes Boyle’s law is .
> The volume of a sample of ideal gas is inversely proportional to the of the gas at constant temperature.
> On the basis of the electronegativity values given in Fig. 12.3, indicate whether each of the following bonds would be expected to be covalent, polar covalent, or ionic. a. S-S b. S-H c. S-K From fig 12.3 21 F Be 3.5 4.0 1.5 20 Ti V Cr Mn L6 16 N
> On the basis of the electronegativity values given in Fig. 12.3, indicate whether each of the following bonds would be expected to be ionic, covalent, or polar covalent. a. O-O b. Al-O c. B-O From fig 12.3 21 F Be 3.5 4.0 1.5 20 Ti V Cr Mn L6 16
> In each of the following groups, which element is the most electronegative? Which is the least electronegative? a. Cs, Ba, At b. Ba, Sr, Ra c. O, Rb, Mg
> The introduction to this chapter says that “we live immersed in a gaseous solution.” What does that mean?
> What factor determines the relative level of polarity of a polar covalent bond?
> A bond between atoms having a (small/large) difference in electronegativity will be ionic.
> Make the indicated pressure conversions. a. 14.9 psi to atmospheres b. 795 torr to atmospheres c. 743 mm Hg to kilopascals d. 99,436 Pa to kilopascals
> The relative ability of an atom in a molecule to attract electrons to itself is called the atom’s .
> What are the common units used to measure pressure? Which unit is an experimental unit derived from the device used to measure atmospheric pressure?
> Describe the type of bonding that exists in the Cl2(g) molecule. How does this type of bonding differ from that found in the HCl(g) molecule? How is it similar?
> In general terms, what is a covalent bond?
> For each of the following sets of pressure/volume data, calculate the missing quantity. Assume that the temperature and the amount of gas remain constant. a. V = 19.3 L at 102.1 kPa; V = 10.0 L at ? kPa b. V = 25.7 mL at 755 torr; V = ? at 761 mm Hg c
> What sorts of elements react to form ionic compounds?
> The energy required to break a given chemical bond is called the .
> Rank the following compounds from lowest to highest melting point. a. CH4 b. MgO c. H2O d. H2S
> Rank the following compounds from lowest to highest boiling point. a. CH3CH2CH2Cl b. CH3CH2Cl c. CH3CH2CH2CH2Cl d. CH3Cl
> Identify the most important type of forces (ionic, hydrogen bonding, dipole–dipole, or London dispersion forces) among atoms or molecules present in the solids of each of the following substances. Solid Forces CF,(CF,CF,),CF, CO2 Na
> Which of the following compound(s) exhibit only London dispersion intermolecular forces? Which compound(s) exhibit hydrogen-bonding forces? Considering only the compounds without hydrogen-bonding interactions, which compounds have dipole–dipole intermole
> The “Chemistry in Focus” segment Diamonds in the Ruff discusses using the ashes of pets to produce diamonds. A diamond is an atomic solid. Why? Why are diamonds also referred to as network solids?
> The “Chemistry in Focus” segment Gorilla Glass discusses the glass currently used for products such as smartphones. Which addition to common glass is not an ionic solid?
> Draw the Lewis structures for the following species to assist you in answering the questions: SeCl2, ICl, BH3, NO2-. a. Which of the species is(are) polar? b. Which of the species exhibits hydrogen-bonding interactions?
> Formaldehyde has the formula CH2O, where C is the central atom. The molecules in a sample of formaldehyde are attracted to each other by a combination of a. dipole–dipole forces and ionic forces. b. hydrogen bonding and dipole–dipole forces. c. ionic
> For each of the following sets of pressure/volume data, calculate the new volume of the gas sample after the pressure change is made. Assume that the temperature and the amount of gas remain the same. a. V = 375 mL at 1.15 atm; V =? mL at 775 mm Hg b.
> Water at 100 °C (its normal boiling point) could certainly give you a bad burn if it were spilled on the skin, but steam at 100 °C could give you a much worse burn. Explain.
> Water is unusual in that its solid form (ice) is less dense than its liquid form. Discuss some implications of this fact.
> The envisions a metal as a cluster of positive ions through which the valence electrons are able to move freely.
> What types of intermolecular forces exist in a crystal of ice? How do these forces differ from the types of intermolecular forces that exist in a crystal of solid oxygen?
> Which type of bonding, ionic or covalent, generally results in higher boiling points? Explain.
> What do we mean when we say a liquid is volatile? Do volatile liquids have large or small vapor pressures? What types of intermolecular forces occur in highly volatile liquids?
> Discuss the types of intermolecular forces acting in the liquid state of each of the following substances. a. Ar b. H2O c. SeO2 d. BF3 (trigonal planar, nonpolar)
> Discuss the types of intermolecular forces acting in the liquid state of each of the following substances. a. N2 b. NH3 c. He d. CO2 (linear, nonpolar)
> For a liquid to boil, the intermolecular forces in the liquid must be overcome. Based on the types of intermolecular forces present, arrange the expected boiling points of the liquid states of the following substances in order from lowest to highest: NaC
> Which is stronger, a dipole–dipole attraction between two molecules or a covalent bond between two atoms within the same molecule? Explain.
> For each of the following sets of pressure/volume data, calculate the new volume of the gas sample after the pressure change is made. Assume that the temperature and the amount of gas remain the same. a. V = 125 mL at 755 mm Hg; V =? mL at 780 mm Hg b.
> The molar heat of vaporization of carbon disulfide, CS2, is 28.4 kJ/mol at its normal boiling point of 46 °C. How much energy (heat) is required to vaporize 1.0 g of CS2 at 46 °C? How much heat is evolved when 50. g of CS2 is condensed from the vapor to
> Why is there no change in intramolecular forces when a solid is melted? Are intramolecular forces stronger or weaker than intermolecular forces?
> Are changes in state physical or chemical changes for molecular solids? Why?
> Some properties of potassium metal are summarized in the following table: Normal melting point…………………….63.5 °C Normal boiling point……………………765.7 °C Molar heat of fusion…………….2.334 kJ/mol Molar heat of vaporization…...79.87 kJ/mol Specific heat of the s
> What is steel?
> Which of the following substances exhibit hydrogen bonding interactions? a. CCl2H2 b. BeF2 c. NO3- d. HCN
> What substitutes for leadership exist for a student preparing to take a final examination in a course offered as part of a company’s educational benefits?
> Is coaching a specific leadership approach or is it another form of mentoring? Explain
> Bounded rationality appears to be a better explanation of how decision making actually occurs. What makes this better than a rational explanation of decision making?
> Creativity requires nonconformity of thinking. Does that explain why so many organizational decisions are noncreative? Aside from the specific techniques discussed in the chapter, what can be done to stimulate creative decision making in an organization?
> Given all the corporate scandals ( e.g.,Volkswagen) that have been in the news, how important a role should ethics play in decision-making? Should leaders and managers—and organizations—be evaluated on the extent to which they make ethical decisions?
> Increasingly today, decisions are made in a global context. Can you think of some techniques that might be employed to reduce the likelihood of difficulties when decision makers from different cultures are working together to solve a problem?
> "Decisions should be thought of as means rather than ends." Explain what this statement means and what affect it should have on decision making.
> Can you think of reasons why some individuals might prefer one-way communications when they are the sender, and two-way when they are the receiver? Explain.
> Discuss some of the advantages of using texting to reach customers as compared with the more traditional methods such as TV, radio, newspapers, magazines, or direct mail.
> Due to the increase in spam and other nonessential e-mail message (e.g., jokes and chain letters) that employees receive, some claim that reading, processing, and responding to e-mail messages can drain employee productivity. What can be done to help emp
> A growing number of Americans work for foreign-owned firms in the United States. Do you think these American employees are being influenced by the approach to management and the culture of the country that owns the firm? Explain.
> Why do you think that downward communication is much more prevalent in organizations than upward communication? How easy would it be to change this?
