Two molecules that contain the same number of each kind of atom but that have different molecular structures are said to be isomers of each other. For example, both ethyl alcohol and dimethyl ether (shown below) have the formula C2H6O and are isomers. Based on considerations of intermolecular forces, which substance would you expect to be more volatile? Which would you expect to have the higher boiling point? Explain. dimethyl ether …………. ethyl alcohol CH3OOOCH3 ………. CH3OCH2OOH
> A mixture at 33 °C contains H2 at 325 torr, N2 at 475 torr, and O2 at 650. torr. a. What is the total pressure of the gases in the system? b. Which gas contains the greatest number of moles?
> An aluminum can contain a small amount of water and is boiled with the lid removed. The heat is then turned off, and the can is sealed. Over time, the can crumples. a. Why doesn’t the can explode or crumple when the water is heated
> If 3.20 g of nitrogen gas occupies a volume of 1.71 L at 0 °C and a pressure of 1.50 atm, what would the volume become if 8.80 g of nitrogen gas were added at constant conditions of temperature and pressure?
> A 22-g sample of neon gas exerts a pressure of 2.0 atm at a certain temperature and volume. What pressure does a 44-g sample of argon gas exert at these conditions of temperature and volume?
> Which of the following statements is(are) true? a. LiF will have a higher vapor pressure at 25 °C than H2S. b. HF will have a lower vapor pressure at 250 °C than HBr. c. Cl2 will have a higher boiling point than Ar. d. HCl is more soluble in water th
> Which of the following statements about intermolecular forces is(are) true? a. London dispersion forces are the only type of intermolecular force that nonpolar molecules exhibit. b. Molecules that have only London dispersion forces will always be gases
> Describe, on a microscopic basis, the processes of evaporation and condensation. Which process requires an input of energy? Why?
> Given each of the following sets of values for three of the gas variables, calculate the unknown quantity. a. P = 1.034 atm; V = 21.2 mL; n = 0.00432 mol; T =? K b. P =? atm; V = 1.73 mL; n = 0.000115 mol; T = 182 K c. P = 1.23 mm Hg; V =? L; n = 0.77
> Make the indicated pressure conversions. a. 1.54 * 105 Pa to atmospheres b. 1.21 atm to pascals c. 97,345 Pa to mm Hg d. 1.32 kPa to pascals
> Given each of the following sets of values for three of the gas variables, calculate the unknown quantity. a. P = 21.2 atm; V = 142 mL; n = 0.432 mol; T =? K b. P =? atm; V = 1.23 mL; n = 0.000115 mol; T = 293 K c. P = 755 mm Hg; V =? mL; n = 0.473 mo
> You have a gas in a container fitted with a piston, and you change one of the conditions of the gas such that a change takes place, as shown below: State three distinct changes you can make to accomplish this, and explain why each would work. volum
> Although the noble gas elements are monatomic and could not give rise to dipole–dipole forces or hydrogen bonding, these elements still can be liquefied and solidified. Explain.
> For each of the following sets of volume/temperature data, calculate the missing quantity. Assume that the pressure and the amount of gas remain constant. a. V = 22.4 L at 0 °C; V = 44.4 L at? K b. V = 1.0 3 1023 mL at 2272 °C; V =? at 25 °C c. V = 32
> Arrange the atoms and/or ions in the following groups in order of decreasing size. a. O, O+, O2- b. Fe2+, Ni2+, Zn2+ c. Ca2+, K+, Cl-
> Describe in detail the microscopic processes that take place when a liquid boils. What kind of forces must be overcome? Are any chemical bonds broken during these processes?
> What are London dispersion forces and how do they arise in a nonpolar molecule? Are London forces typically stronger or weaker than dipole–dipole attractions between polar molecules? Are London forces stronger or weaker than covalent bonds? Explain.
> A particular balloon is designed by its manufacturer to be inflated to a volume of no more than 2.5 L. If the balloon is filled with 2.0 L of helium at sea level, is released, and rises to an altitude at which the atmospheric pressure is only 500. mm Hg,
> Consider the following series of atoms or ions: S2-, S, S2+, Cs+, Sr2+. a. Which of the species has the smallest size? b. Which of the species has the largest ionization energy?
> What do we call the energies required, respectively, to melt and to vaporize 1 mole of a substance? Which of these energies is always larger for a given substance? Why?
> Convert the following pressures into pascals. a. 774 torr b. 0.965 atm c. 112.5 kPa d. 801 mm Hg
> 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 = 123 L at 4.56 atm; V =? at 1002 mm Hg b. V = 634 mL at 25.2 mm Hg; V = 166 mL at? atm c.
> A 2.50-L container at 1.00 atm and 248°C is filled with 5.41 g of a monatomic gas. a. Determine the identity of the gas. b. Assuming the 2.50-L container is a large elastic balloon, predict what will happen when 10.0 g of oxygen gas is added to the bal
> Cake mixes and other packaged foods that require cooking often contain special directions for use at high elevations. Typically these directions indicate that the food should be cooked longer above 5000 ft. Explain why it takes longer to cook something a
> Describe, on both a microscopic and a macroscopic basis, what happens to a sample of water as it is cooled from room temperature to 50 °C below its normal freezing point.
> What are some important uses of water, both in nature and in industry? What is the liquid range for water?
> As weather balloons rise from the earth’s surface, the pressure of the atmosphere becomes less, tending to cause the volume of the balloons to expand. However, the temperature is much lower in the upper atmosphere than at sea level. Would this temperatur
> Why is the molecular structure of H2O nonlinear, whereas that of BeF2 is linear, even though both molecules consist of three atoms?
> Carbon dioxide gas, saturated with water vapor, can be produced by the addition of aqueous acid to calcium carbonate. CaCO3(s) + 2H+(aq) / Ca2+(aq) + H2O(l) + CO2(g) How many moles of CO2(g), collected at 60. °C and 774 torr total pressure, are produced
> A helium tank contains 25.2 L of helium at 8.40 atm pressure. Determine how many 1.50-L balloons at 755 mm Hg can be inflated with the gas in the tank, assuming that the tank will also have to contain He at 755 mm Hg after the balloons are filled (that i
> When ammonium carbonate is heated, three gases are produced by its decomposition. (NH4)2CO3(s) 2NH3(g) + CO2(g) + H2O(g) What total volume of gas is produced, measured at 453 °C and 1.04 atm, if 52.0 g of ammonium carbonate is
> In each of the following groups, which element is the most electronegative? Which is the least electro negative? a. K, Na, H b. F, Br, Na c. B, N, F
> Write a Lewis structure for each of the following simple molecules. Show all bonding valence electron pairs as lines and all nonbonding valence electron pairs as dots. a. GeH4 b. ICl c. NI3 d. PF3
> What is the total number of valence electrons in each of the following molecules? a. HNO3 b. H2SO4 c. H3PO4 d. HClO4
> When a person has a severe fever, one therapy to reduce the fever is an “alcohol rub.” Explain how the evaporation of alcohol from the person’s skin removes heat energy from the body.
> Consider the flasks in the following diagrams. Assuming the connecting tube has negligible volume, draw what each diagram will look like after the stopcock between the two flasks is opened. Also, solve for the final pressure in each case, in terms of t
> Which of the following statements is(are) true? a. At constant temperature, the lighter the gas molecules, the faster the average velocity of the gas molecules. b. At constant temperature, the heavier the gas molecules, the larger the average kinetic e
> On the basis of their electron configurations, predict the formula of the simple binary ionic compound likely to form when the following pairs of elements react with each other. a. sodium, Na, and selenium, Se b. rubidium, Rb, and fluorine, F c. potas
> What is an alloy? Explain the differences in structure between substitutional and interstitial alloys. Give an example of each type.
> What is a network solid? Give an example of a network solid and describe the bonding in such a solid. How does a network solid differ from a molecular solid?
> During the making of steel, iron(II) oxide is reduced to metallic iron by treatment with carbon monoxide gas. FeO(s) + CO(g) / Fe(s) + CO2(g) Suppose 1.45 kg of Fe reacts. What volume of CO(g) is required, and what volume of CO2(g) is produced, each mea
> Explain the overall trend in the following melting points in terms of the forces among particles in the solids indicated. Hydrogen, H2………………….-259 °C Ethyl alcohol, C2H5OH………-114 °C Water, H2O……………………….…0 °C Sucrose, C12H22O11…………...186 °C Calcium chlo
> Describe in detail the microscopic processes that take place when a solid melts and when a liquid boils. What kind of forces must be overcome? Are any chemical bonds broken during these processes?
> In general terms, what is a chemical bond?
> On the basis of the electronegativity values given in Fig. 12.3, indicate which is the more polar bond in each of the following pairs. a. N-P or N-O b. N-C or N-O c. N-S or N-C d. N-F or N-S
> Dinitrogen monoxide, N2O, reacts with propane, C3H8, to form nitrogen, N2; carbon dioxide, CO2; and water, H2O. a. Write a balanced chemical equation for this reaction, treating all substances as gases. Include phases in your equation. b. Two reservoir
> A mixture contains 5.00 g each of O2, N2, CO2, and Ne gas. Calculate the volume of this mixture at STP. Calculate the partial pressure of each gas in the mixture at STP.
> The forces holding together a molecular solid are much (stronger/ weaker) than the forces between particles in an ionic solid.
> A common prank on college campuses is to switch the salt and sugar on dining hall tables, which is usually easy because the substances look so much alike. Yet, despite the similarity in their appearance, these two substances differ greatly in their prope
> Consider the following unbalanced chemical equation in which element X is unknown: X(s) + F2(g) ( XF3(s) If 9.15 g of element X(s) is completely reacted with 4.00 L of fluorine gas at 250 °C and 2.50 atm, what is the identity of X?
> If water is added to magnesium nitride, ammonia gas is produced when the mixture is heated. Mg3N2(s) + 3H2O(l) 3MgO(s) + 2NH3(g) If 10.3 g of magnesium nitride is treated with water, what volume of ammonia gas would be co
> Although we generally think of combustion reactions as involving oxygen gas, other rapid oxidation reactions are also referred to as combustions. For example, if magnesium metal is placed into chlorine gas, a rapid oxidation takes place, and magnesium ch
> Calcium carbide, CaC2, reacts with water to produce acetylene gas, C2H2. CaC2(s) + 2H2O(l) C2H2(g) + Ca(OH)2(s) What volume of acetylene at 25 °C and 1.01 atm is generated by the complete reaction of 2.49 g of calcium carbide? What
> Explain the difference between intramolecular and intermolecular forces.
> Ammonia and gaseous hydrogen chloride combine to form ammonium chloride. NH3(g) + HCl(g) NH4Cl(s) If 4.21 L of NH3(g) at 27 °C and 1.02 atm is combined with 5.35 L of HCl(g) at 26 °C and 0.998 atm, what mass of NH4Cl(s) will be produced
> For each of the following molecules, predict both the molecular structure and bond angles around the central atom. a. SeS2 b. SeS3 c. SO2 d. CS2
> Consider the following reaction for the combustion of octane, C8H18: 2C8H18(l) + 25O2(g) / 16CO2(g) + 18H20(l) What volume of oxygen gas at STP would be needed for the complete combustion of 10.0 g of octane?
> Which substance in each pair would be expected to be more volatile at a particular temperature? Explain your reasoning. a. H2O(l) or H2S(l) b. H2O(l) or CH3OH(l) c. CH3OH(l) or CH3CH2OH(l)
> Calcium oxide can be used to “scrub” carbon dioxide from air. CaO(s) + CO2(g) CaCO3(s) What mass of CO2 could be absorbed by 1.25 g of CaO? What volume would this CO2 occupy at STP?
> Using the VSEPR theory, predict the molecular structure of each of the following polyatomic ions. a. dihydrogen phosphate ion, H2PO4- b. perchlorate ion, ClO4- c. sulfite ion, SO32-
> Which substance in each pair would be expected to have a lower boiling point? Explain your reasoning. a. CH3OH or CH3CH2CH2OH b. CH3CH3 or CH3CH2OH c. H2O or CH4
> Explain, in terms of the kinetic molecular theory, how an increase in the temperature of a gas confined to a rigid container causes an increase in the pressure of the gas.
> How is the phenomenon of temperature explained on the basis of the kinetic molecular theory? What microscopic property of gas molecules is reflected in the temperature measured?
> Consider the following molecules: CH3OH, CH4, H2O, C2H6. a. Draw the Lewis structure for each molecule, and indicate whether each is polar or nonpolar. b. At room temperature, two of these compounds exist as a liquid, and two of these compounds exist a
> What does it mean to say that a bond is polar? Give two examples of molecules with polar bonds. Indicate in your examples the direction of the polarity.
> For the indicated atom in each of the following molecules or ions, give the number and arrangement of the electron pairs around that atom. a. As in AsO43- b. Se in SeO42- c. S in H2S
> Small quantities of hydrogen gas can be prepared in the laboratory by the addition of aqueous hydrochloric acid to metallic zinc. Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g) Typically, the hydrogen gas is bubbled through water for collection and
> Although the valence electron pairs in ammonia have a tetrahedral arrangement, the overall geometric structure of the ammonia molecule is not described as being tetrahedral. Explain.
> Suppose that 1.28 g of neon gas and 2.49 g of argon gas are confined in a 9.87-L container at 27 °C. What would be the pressure in the container?
> If a gaseous mixture is made of 2.41 g of He and 2.79 g of Ne in an evacuated 1.04-L container at 25 °C, what will be the partial pressure of each gas and the total pressure in the container?
> What general principles determine the molecular structure (shape) of a molecule?
> We often collect small samples of gases in the laboratory by bubbling the gas into a bottle or flask containing water. Explain why the gas becomes saturated with water vapor and how we must take the presence of water vapor into account when calculating t
> Determine the partial pressure of each gas as shown in this figure. Note: The relative numbers of each type of gas are depicted in the figure. 1.00 atm о Не Ne Ar
> Explain why the measured properties of a mixture of gases depend only on the total number of moles of particles, not on the identity of the individual gas particles. How is this observation summarized as a law?
> What mass of neon gas would be required to fill a 3.00-L flask to a pressure of 925 mm Hg at 26 °C? What mass of argon gas would be required to fill a similar flask to the same pressure at the same temperature?
> What evidence do we have that the solid form of water is less dense than the liquid form of water at its freezing/melting point?
> A tank contains a mixture of 52.5 g of oxygen gas and 65.1 g of carbon dioxide gas at 27 °C. The total pressure in the tank is 9.21 atm. Calculate the partial pressure (in atm) of each gas in the mixture.
> Write a Lewis structure for each of the following polyatomic ions. Show all bonding valence electron pairs as lines and all nonbonding valence electron pairs as dots. For those ions that exhibit resonance, draw the various possible resonance forms. a. c
> Write a Lewis structure for each of the following polyatomic ions. Show all bonding valence electron pairs as lines and all nonbonding valence electron pairs as dots. For those ions that exhibit resonance, draw the various possible resonance forms. a. c
> Write a Lewis structure for each of the following polyatomic ions. Show all bonding valence electron pairs as lines and all nonbonding valence electron pairs as dots. For those ions that exhibit resonance, draw the various possible resonance forms. a. c
> Write a Lewis structure for each of the following polyatomic ions. Show all bonding valence electron pairs as lines and all nonbonding valence electron pairs as dots. For those ions that exhibit resonance, draw the various possible resonance forms. a. s
> Consider Fig. 14.10. Imagine you are talking to a friend who has not taken any science courses, and explain how the figure demonstrates the concept of vapor pressure and enables it to be measured. From figure 14.10 Diethyl ather vapor -Vacuum -H;O v
> What do we mean by a dynamic equilibrium? Describe how the development of a vapor pressure above a liquid represents such an equilibrium.
> In carbon compounds a given group of atoms can often be arranged in more than one way. This means that more than one structure may be possible for the same atoms. For example, both the molecules diethyl ether and 1-butanol have the same number of each ty
> Write a Lewis structure for each of the following simple molecules. Show all bonding valence electron pairs as lines and all nonbonding valence electron pairs as dots. a. C2H6 b. NF3 c. C4H10 d. SiCl4
> Write a Lewis structure for each of the following simple molecules. Show all bonding valence electrons pairs as lines and all nonbonding valence electron pairs as dots. a. H2S b. SiF4 c. C2H4 d. C3H8
> Compare and contrast the bonding found in the H2 (g) and HF(g) molecules with that found in NaF(s).
> Write a Lewis structure for each of the following simple molecules. Show all bonding valence electron pairs as lines and all nonbonding valence electron pairs as dots. a. NBr3 b. HF c. CBr4 d. C2H2
> Give the total number of valence electrons in each of the following molecules. a. B2O3 b. CO2 c. C2H6O d. NO2
> Give the total number of valence electrons in each of the following molecules. a. N2O b. B2H6 c. C3H8 d. NCl3
> If you’ve ever opened a bottle of rubbing alcohol or other solvent on a warm day, you may have heard a little “whoosh” as the vapor that had built up above the liquid escapes. Describe on a microscopic basis how a vapor pressure builds up in a closed con
> What mass of helium gas is needed to pressurize a 100.0-L tank to 255 atm at 25 °C? What mass of oxygen gas would be needed to pressurize a similar tank to the same specifications?
> Given each of the following sets of values for an ideal gas, calculate the unknown quantity. a. P = 782 mm Hg; V =? n = 0.210 mol; T = 27 °C b. P =? mm Hg; V = 644 mL; n = 0.0921 mol; T = 303 K c. P = 745 mm Hg; V = 11.2 L; n = 0.401 mol; T =? K
> Show how Charles’s gas law can be derived from the ideal gas law.
> Show how Boyle’s gas law can be derived from the ideal gas law.
> What do we mean by an ideal gas?
> Explain what the “duet” and “octet” rules are and how they are used to describe the arrangement of electrons in a molecule.
> Consider a sample of ice being heated from -5 °C to +5 °C. Describe on both a macroscopic and a microscopic basis what happens to the ice as the temperature reaches 0 °C.
> Given the following sets of values for three of the gas variables, calculate the unknown quantity. a. P = 782.4 mm Hg; V = ?; n = 0.1021 mol; T = 26.2 °C b. P = ? mm Hg; V = 27.5 mL; n = 0.007812 mol; T = 16.6 °C c. P = 1.045 atm; V = 45.2 mL; n = 0.00
> For each of the following pairs, indicate which is larger. a. I or F b. F or F- c. Na+ or F-
> For each of the following pairs, indicate which is smaller. a. Fe or Fe3+ b. Cl or Cl- c. Al3+ or Na+
