Chem Unit 3 3.1-3.7

3.5 Kinetic Molecular Theory 13. At 27°C, a rigid 2.0 L vessel is filled with N2(g) and sealed. The initial pressure of N2(g) is 720 mm Hg. The vessels is then heated to 127°C and allowed to reach a constant pressure. The gas particles in the vessel at 27°C are represented in the diagram at right. The lengths of the arrows represent the speeds of the particles. Which of the following diagrams best represents the particles when the vessel is heated to 127°C? all the choices are diagrams

A

3.5 Kinetic Molecular Theory 7. The diagram below shows the distribution of speeds for a sample of N2(g) at 25 °C. There is a graph Which of the following graphs shows the distribution of speeds for a sample of O2(g) at 25°C (dashed line)? all the answer choices are graphs

A

3.3 Solids, Liquids, and Gases 9. Which of the following diagrams correctly depicts a solution in which MgCl 2 has been completely dissolved? There are diagrams A. diagram with 2 Mg2+ and 2 Cl- B. diagram with 2 Mg2+ and 3 Cl- C. diagram with 4 Mg2+ and 2 Cl- D. diagram with 2 Mg2+ and 4 Cl-

D. diagram with 2 Mg2+ and 4 Cl-

3.7 Solutions and Mixtures 10. If 50. mL of 1.0 M NaOH is diluted with distilled water to a volume of 2.0 L, the concentration of the resulting solution is a. 0.025 M b. 0.050 M c. 0.10 M d. 0.50 M e. 1.0 M

a. 0.025 M

3.7 Solutions and Mixtures 7. How many grams of CaCl2 are needed to prepare 100.0 mL of 0.100 M Cl−(aq) ions? a. 0.555 g b. 1.11 g c. 2.22 g d. 5.55 g

a. 0.555 g

3.1 IMFs 6. The London (dispersion) forces are weakest for which of the following gases under the same conditions of temperature and pressure? a. H2 b. O2 c. F2 d. N2

a. H2

3.6 Ideal Gas Law 3. Which of the following behaves most like an ideal gas at the conditions indicated? a. H2(g) molecules at 10-3 atm and 200°C b. O2(g) molecules at 20 atm and 200°C c. SO2(g) molecules at 20 atm and 200°C d. NH3(g) molecules at 20 atm and 200°C e. NH3(g) molecules at 20 atm and 300°C

a. H2(g) molecules at 10-3 atm and 200°C

3.6 Ideal Gas Law 9. Which gas would be least ideal at the same conditions of temperature and pressure? a. H2O(g) b. He(g) c. O2(g) d. CO(g)

a. H2O(g)

3.5 Kinetic Molecular Theory 1. A 0.5 mol sample of He(g) and a 0.5 mol sample of Ne(g) are placed separately in two 10.0 L rigid containers at 25°C. Each container has a pinhole opening. Which of the gases, He(g) or Ne(g), will escape faster through the pinhole and why? a. He(g) will escape faster because the He(g) atoms are moving at a higher average speed than the Ne(g) atoms. b. Ne(g) will escape faster because its initial pressure in the container is higher. c. Ne(g) will escape faster because the Ne(g) atoms have a higher average KE than the He(g) atoms. d. Both gases will escape at the same rate because the atoms of both gases have the same average KE.

a. He(g) will escape faster because the He(g) atoms are moving at a higher average speed than the Ne(g) atoms.

3.6 Ideal Gas Law 15. Which of the following best helps explain why the pressure of a sample of CH4(g) (molar mass 16 g/mol) is closer to the pressure predicted by the ideal gas law than a sample of NH3(g) (molar mass 17g/mol)? a. NH3 molecules are polar while CH4 molecules are not, and the greater attractions between NH3 molecules cause the molecules to collide with the walls of the container with less force. b. NH3 molecules have a greater molar mass than CH4 molecules, so the NH3 molecules collide with the walls of the container with more force. c. CH4 molecules have more hydrogen atoms than NH3 molecules, so CH4 molecules have more hydrogen bonding and greater intermolecular forces. d. CH4 molecules are larger than NH3 molecules, so the actual CH4 molecules take up a significant portion of the volume of the gas.

a. NH3 molecules are polar while CH4 molecules are not, and the greater attractions between NH3 molecules cause the molecules to collide with the walls of the container with less force.

3.2 Properties of Solids 13. Which of the following is most likely to be a solid at room temperature? a. Na2S b. HF c. NH3 d. N2

a. Na2S

3.5 Kinetic Molecular Theory 5. Equal numbers of moles of He(g), Ar(g), and Ne(g) are placed in a glass vessel at room temperature. If the vessel has a pinhole-sized leak, which of the following will be true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused? a. PHe < PNe < PAr b. PHe < PAr < PNe c. PNe < PAr < PHe d. PAr < PHe < PNe e. PHe = PAr = PNe

a. PHe < PNe < PAr

3.6 Ideal Gas Law 5. Which of the following gases deviates most from ideal behavior? a. SO2 b. Ne c. CH4 d. N2 e. H2

a. SO2

3.6 Ideal Gas Law 4. Ar(g) deviates more from ideal behavior at extremely high pressures than Ne(g) does. Which of the following is one reason for this difference? a. The particle volume of Ar is greater than that of Ne b. Ar atoms have more valence electrons than Ne atoms have, so Ar atoms have greater interparticle forces. c. The intermolecular forces between Ne atoms are greater than those between Ar atoms. d. Ar atoms are more attracted to the walls of the container than Ne atoms are.

a. The particle volume of Ar is greater than that of Ne

3.2 Properties of Solids 12. The properties of this solid can be attributed to: a. an interlocking pattern of atoms b. intermolecular hydrogen bonding c. the electron-sea model d. strong ion-ion interactions

a. an interlocking pattern of atoms

3.5 Kinetic Molecular Theory 4. At standard temperature and pressure, a 0.50 mol sample of H2 gas and a separate 1.0 mol sample of O2 gas have the same a. average molecular kinetic energy b. average molecular speed c. volume d. density

a. average molecular kinetic energy

3.6 Ideal Gas Law 2. One reason that a real gas deviates from an ideal gas is that the molecules of a real gas have: a. forces of attraction for each other b. no net loss of energy during collisions c. a negligible volume d. a straight-line motion

a. forces of attraction for each other

3.2 Properties of Solids 2. A sample of a hard, solid binary compound at room temperature did not conduct electricity as a pure solid but became highly conductive when dissolved in water. Which of the following types of interactions is most likely found between the particles in the substance? a. ionic bonds b. covalent bonds c. metallic bonds d. hydrogen bonds

a. ionic bonds

3.2 Properties of Solids 10. The solid might be: a. quartz, SiO2 b. tin, Sn c. rock salt, NaCl d. table sugar, C6H12O6

a. quartz, SiO2

3.6 Ideal Gas Law 6. When the actual gas volume is greater than the volume predicted by the ideal gas law, the explanation lies in the fact that the ideal gas law does NOT include a factor for molecular a. volume b. mass c. velocity d. attractions e. shape

a. volume

3.7 Solutions and Mixtures 11. Solid Al(NO3)3 is added to distilled water to produce a solution in which the concentration of nitrate, [NO3-], is 0.10 M. What is the concentration of aluminum ion, [Al3+], in this solution? a. 0.010 M b. 0.033 M c. 0.066 M d. 0.10 M e. 0.30 M

b. 0.033 M

3.4 Ideal Gas Law 10. A 2 L sample of N2(g)and a 1 L sample of Ar(g), each originally at 1 atm and 0°C, are combined in a 1 L tank. If the temperature is held constant, what is the total pressure of the gases in the tank? a. 2 atm b. 3 atm c. 4 atm d. 5 atm

b. 3 atm

3.4 Ideal Gas Law 3. The figure below represents three sealed 1.0 L vessels, each containing a different inert gas at 298 K. The pressure of Ar in the first vessel is 2.0 atm. The ratio of the numbers of Ar, Ne, and He atoms in the vessels is 2: 1: 6, respectively. After all the gases are combined in a previously evacuated 2.0 L vessel, what is the total pressure of the gases at 298 K? a. 3.0 atm b. 4.5 atm c. 9.0 atm d. 18 atm

b. 4.5 atm

3.7 Solutions and Mixtures 9. A student wishes to prepare 2.00 liters of 0.100 M KIO3 (molecular weight 214). The proper procedure is to weigh out: a. 42.8 g of KIO3 and add 2.00 kg of H2O b. 42.8 g of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 L c. 21.4 g of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 L d. 42.8 g of KIO3 and add 2.00 L of H2O e. 21.4 g of KIO3 and add 2.00 L of H2O

b. 42.8 g of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 L

3.4 Ideal Gas Law 2. In which of the following is it impossible to predict whether the pressure of a gas will increase, decrease, or stay the same? a. A gas sample is heated. b. A gas sample is heated, and the volume is increased. c. A gas sample is cooled, and some gas is withdrawn. d. Additional gas is added to a sample of gas.

b. A gas sample is heated, and the volume is increased.

3.5 Kinetic Molecular Theory 6. The following question refers to the 1.0 L flasks shown below. In which flask do the molecules have the greatest average speed? There is a picture a. A b. B c. C d. D e. E

b. B

3.2 Properties of Solids 15. The structure of one form of boron nitride is represented below. This form of boron nitride is one of the hardest substances known. Which of the following best helps explain why boron nitride is so hard? There is a picture a. Boron ions and nitrogen ions are held together by ionic bonds. b. Boron nitride is a network solid of atoms connected by covalent bonds with fixed bond angles. c. Boron nitride is an alloy, and alloys are typically harder than the elements used to make them. d. Boron nitride is a polymer made of long chains of boron atoms and nitrogen atoms held together by London Dispersion Forces.

b. Boron nitride is a network solid of atoms connected by covalent bonds with fixed bond angles.

3.2 Properties of Solids 1. The ionic compounds NaCl and MgS are represented by the diagrams below. Which statement correctly identifies diagram 1 and identifies the compound with the lower melting point, explaining why? There is a diagram a. Diagram 1 represents NaCl; it has a lower melting point than MgS because the coulombic attractions between the singly charged Na+ ions and the Cl- ions in NaCl are stronger than those between the ions in MgS. b. Diagram 1 represents NaCl; it has a lower melting point than MgS because the coulombic attractions between its singly charged Na+ ions and the Cl- ions are weaker than those between the ions in MgS. c. Diagram 1 represents MgS; it has a lower melting point than NaCl because the coulombic attractions between its doubly charged Mg2+ ions and the S2- ions are stronger than those between the ions in NaCl. d. Diagram 1 represents MgS; it has a lower melting poi

b. Diagram 1 represents NaCl; it has a lower melting point than MgS because the coulombic attractions between its singly charged Na+ ions and the Cl- ions are weaker than those between the ions in MgS.

3.6 Ideal Gas Law 14. Which of the following would, in the gas phases, display the greatest deviations from ideal gas behavior? a. C2H2 b. HCl c. BrCl d. Se2

b. HCl

3.6 Ideal Gas Law 1. Under what conditions do real gases behave most like an ideal gas? a. Low temperature and low pressure b. High temperature and low pressure c. Low temperature and high pressure d. High temperature and high pressure

b. High temperature and low pressure

3.5 Kinetic Molecular Theory 16. For the graphs below, there is a change to some property, characteristic, or quantity. For each: a. Sketch the new shape of the distribution curve. b. Indicate the most probable energy (Emp) if its changes. c. Indicate the new activation energy (Ea) if it changes. d. Indicate whether the number of particles with energy > Ea increases, remains the same, or decreases.

b. Indicate the most probable energy (Emp) if its changes.

3.2 Properties of Solids 6. Which of the following could be the identity of a white crystalline solid that exhibits the following properties? • It melts at 320°C. • It does not conduct electricity as a solid. • It conducts electricity in an aqueous solution. a. C6H12O6(s) b. NaOH(s) c. SiO2(s) d. Cu(s)

b. NaOH(s)

3.6 Ideal Gas Law 11. The diagrams opposite represent two samples of Xe gas in containers of equal volume at 280K. Which of the following correctly compares the two samples in terms of their deviation from ideal gas behavior and explains why? a. The gas in sample 1 would deviate more from ideal behavior because the average distance an Xe atom travels before colliding with another Xe atom is greater. b. The gas in sample 2 would deviate more from ideal behavior because the Xe atoms are closer together, leading to an increase in intermolecular attractions. c. The gas in sample 2 would deviate more from ideal behavior because the average speed of the Xe atoms is less, leading to an increase in intermolecular attractions. d. The gases in both sample 1 and sample 2 would show the same deviation from ideal behavior.

b. The gas in sample 2 would deviate more from ideal behavior because the Xe atoms are closer together, leading to an increase in intermolecular attractions.

3.4 Ideal Gas Law 5. When a sample of oxygen gas in a closed container of constant volume is heated until its absolute temperature is doubled, which of the following is also doubled? a. The density of the gas b. The pressure of the gas c. The average velocity of the gas molecules d. The number of molecules per cm3

b. The pressure of the gas

3.4 Ideal Gas Law 6. The reaction between NO(g) and O2(g) to produce NO2(g) in a rigid reaction vessel is represented in the diagram below. The pressure inside the container is recorded using a pressure gauge. Which of the following statements correctly predicts the change in pressure as the reaction goes to completion at constant temperature, and provides the correct explanation? There is a picture a. The pressure will increase because the product molecules have a greater mass than either of the reactant molecules. b. The pressure will decrease because there are fewer molecules of product than of reactants. c. The pressure will decrease because the product molecules have a lower average speed than the reactant molecules. d. The pressure will not change because the total mass of the product molecules is the same as the total mass of the reactant molecules.

b. The pressure will decrease because there are fewer molecules of product than of reactants.

3.3 Solids, Liquids, and Gases 5. Of the following, the best explanation for the fact that most gases are easily compressed is that the molecules in a gas: a. are in constant motion b. are relatively far apart c. have relatively small masses d. have a real, nonzero volume

b. are relatively far apart

3.2 Properties of Solids 9. A solid is a poor conductor of electricity, is very hard, has a high melting point, and is non-brittle. The solid is probably a. molecular b. covalent network c. ionic d. metallic

b. covalent network

3.7 Solutions and Mixtures 3. The dissolution of water in octane (C8H18) is prevented by ___. a. London dispersion forces between water molecules b. hydrogen bonding between water molecules c. dipole-dipole attractions between octane molecules d. ion-dipole attraction between water and octane molecules

b. hydrogen bonding between water molecules

3.6 Ideal Gas Law 10. When considering energy of ideal gases, we assume that they have a. both molecular kinetic energy and molecular potential energy b. molecular kinetic energy but not molecular potential energy c. molecular potential energy but not molecular kinetic energy d. neither molecular kinetic energy nor molecular potential energy

b. molecular kinetic energy but not molecular potential energy

3.7 Solutions and Mixtures 6. How many moles of Na + ions are in 100.0 mL of 0.100 M Na3PO4(aq)? a. 0.300 mol b. 0.100 mol c. 0.0300 mol d. 0.0100 mol

c. 0.0300 mol

3.6 Ideal Gas Law 19. Under which of the following conditions of temperature and pressure will H2 gas be expected to behave most like an ideal gas? a. 50 K and 0.10 atm b. 50 K and 5.0 atm c. 500 K and 0.10 atm d. 500 K and 50 atm

c. 500 K and 0.10 atm

3.6 Ideal Gas Law 16. Under which of the following conditions of temperature and pressure would 1.0 mol of the real gas CO 2(g) behave most like an ideal gas? Temperature (K) Pressure (atm) a. 100 0.1 b. 100 100 c. 800 0.1 d. 800 100

c. 800 0.1

3.4 Ideal Gas Law 8. A gas mixture at 0°C and 1.0 atm contains 0.010 mol of H2, 0.015 mol of O2, and 0.025 mol of N2. Assuming ideal behavior, what is the partial pressure of hydrogen gas (H2) in the mixture? a. About 0.010 atm, because there is 0.010 mol of H2 b. About 0.050 atm, because there is 0.050 mol of gases at 0°C and 1.0 atm. c. About 0.20 atm, because H2 compromises 20% of the total number of moles of gas. d. About 0.40 atm, because the mole ratio of H : O : N is 0.4 : 0.6 : 1. 222

c. About 0.20 atm, because H2 compromises 20% of the total number of moles of gas.

3.7 Solutions and Mixtures 4. Which of the following statements is correct regarding the state of energy in solution formation? There is a picture a. Energy is first released in the breaking of solvent particles and then absorbed in when solute particles become solvated. b. Energy is absorbed in all three stages of solution formation. c. Energy is absorbed in the first two stages of solution formation and then released as solute particles become solvated. d. Energy is first released in the breaking of solute particles and then absorbed when solute particles become solvated.

c. Energy is absorbed in the first two stages of solution formation and then released as solute particles become solvated.

3.2 Properties of Solids 14. Which characteristic is most closely associated with covalent network solids? a. High thermal conductivity, high degree of hardness. b. High electrical conductivity, high thermal conductivity. c. High melting points, high degree of hardness. d. High ductility, low electrical conductivity.

c. High melting points, high degree of hardness.

3.1 IMFs 7. Which of the following is the strongest type of interaction that occurs between the atoms within the circled areas of the two molecules represented at right? a. Polar covalent bond b. Non-polar covalent bond c. Hydrogen bonding d. London Dispersion Forces

c. Hydrogen bonding

3.5 Kinetic Molecular Theory 3. A sample of an ideal gas is cooled from 50.0°C to 25.0°C in a sealed container of constant volume. Which of the following values for the gas will decrease? I. The average molecular mass of the gas II. The average distance between the molecules III. The average speed of the molecules a. I only b. II only c. III only d. I and III e. II and III

c. III only

3.2 Properties of Solids 8. At room temperature I2(s) is a molecular solid. Which of the following provides a characteristic of I2(s) with a correct explanation? a. It has a high melting point because it has weak intermolecular forces. b. It is hard because it forms a three-dimensional covalent network. c. It's not a good conductor of electricity because its valence electrons are localized in bonding and lone pairs. d. It is very soluble in water because its molecules are polar.

c. It's not a good conductor of electricity because its valence electrons are localized in bonding and lone pairs.

3.7 Solutions and Mixtures 2. If all of the following molecules are equimolar, which is the strongest electrolyte? a. NaCl b. HCl c. MgCl2 d. C6H12O6

c. MgCl2

3.5 Kinetic Molecular Theory 15. Based on the Maxwell-Boltzmann graph below, which of the following statements is TRUE? There is a graph a. T1 is at a higher temperature than T2, so more molecules will react to form products. b. The reaction is exothermic, so increasing kinetic energy decreases the rate of the reaction. c. T2 is at a higher temperature than T1, so more molecules will react to form products. d. The reaction is endothermic, so increasing kinetic energy increases the rate of the reaction.

c. T2 is at a higher temperature than T1, so more molecules will react to form products.

3.5 Kinetic Molecular Theory 10. Two flexible containers for gases are at the same temperature and pressure. One holds 0.50 g of hydrogen and the other holds 8.0 g of oxygen. Which of the following statements regarding these gas samples is FALSE? a. The volume of the hydrogen container is the same as the volume of the oxygen container. b. The number of molecules in the hydrogen container is the same as the number of molecules in the oxygen container. c. The average kinetic energy of the hydrogen molecules is the same as the average kinetic energy of the oxygen molecules. d. The average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules.

c. The average kinetic energy of the hydrogen molecules is the same as the average kinetic energy of the oxygen molecules.

3.5 Kinetic Molecular Theory 11. The volume of a sample of air in a cylinder with a movable piston is 2.0 L at a pressure P 1, as shown in the diagram below. There is a diagram The volume is increased to 5.0 L as the temperature is held constant. The pressure of the air in the cylinder is now P2. What effect do the volume and pressure changes have on the average kinetic energy of the molecules in the sample? a. The average kinetic energy increases. b. The average kinetic energy decreases. c. The average kinetic energy stays the same. d. It cannot be determined how the kinetic energy is affected without knowing P1 and P2.

c. The average kinetic energy stays the same.

3.5 Kinetic Molecular Theory 2. A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature? a. The volume of the gas increases. b. The pressure of the gas decreases. c. The average speed of the gas molecules remains the same. d. The average distance between the gas molecules increases.

c. The average speed of the gas molecules remains the same.

3.1 IMFs 3. Four different liquid compounds in flasks at are represented at right. The table below identifies the compounds. Flask C shows the most particles in the vapor phase. There is a table and a graph Which of the following is not shown in the model but best helps to explain why flask C must contain pentane? a. The random motion of the particles within the liquids. b. The relative speeds of the vapor particles in each flask. c. The strength of the intermolecular forces between the particles in the liquids. d. The structural formula of the molecules of the liquid and vapor in each flask.

c. The strength of the intermolecular forces between the particles in the liquids.

3.3 Solids, Liquids, and Gases 7. At room temperature, F2 and Cl2 are gases, Br2 is a liquid and I2 is a solid. This is because: a. dipole-dipole interactions increase with molar mass. b. polarity increases with molar mass. c. dispersion interactions increase with polarizable electrons. d. dispersion interactions increase with polarizable electrons and polarity increases with molecular mass.

c. dispersion interactions increase with polarizable electrons.

3.3 Solids, Liquids, and Gases 6. The vapor pressure of a liquid increases with increasing temperature principally because the: a. strength of the intermolecular forces increases. b. average molecular mass increases. c. fraction of high energy molecules increases much faster than the average energy. d. atmospheric pressure increases

c. fraction of high energy molecules increases much faster than the average energy.

3.4 Ideal Gas Law 4. This question refer to three gases in identical rigid containers under the conditions given in the table below. The density of the gas, in g/L, is a. greatest in container A b. greatest in container C c. greatest in container B d. The same for all three containers

c. greatest in container B

3.6 Ideal Gas Law 17. The table below contains information about samples of four different gases at 273 K. The samples are in four identical rigid containers numbered 1 through 4. There is a chart The best explanation for the lower pressure in container 4 is that SO2 molecules a. have a larger average speed than the other three gases b. occupy a larger portion of the container volume than the other three gases c. have stronger intermolecular attractions than the other three gases d. contain p bonds, while the other gases contain only σ bonds

c. have stronger intermolecular attractions than the other three gases

3.6 Ideal Gas Law 13. What gases deviate most from ideal behavior? a. polar molecules with small molar masses b. nonpolar molecules with small molar masses c. polar molecules with large molar masses d. nonpolar molecules with large molar masses

c. polar molecules with large molar masses

3.3 Solids, Liquids, and Gases 8. On a relative basis, the weaker the intermolecular forces in a substance, a. the greater its heat of vaporization b. the more it deviates from ideal gas behavior c. the greater its vapor pressure at a particular temperature d. the higher its melting point

c. the greater its vapor pressure at a particular temperature

3.7 Solutions and Mixtures 13. What is the molarity of I-(aq) in a solution that contains 34.0 g of SrI2 (molar mass 341 g) in 1.0 L of the solution? a. 0.034 M b. 0.068 M c. 0.10 M d. 0.20 M e. 0.68 M

d. 0.20 M

3.7 Solutions and Mixtures 8. For an experiment, a student needs 100.0 mL of 0.4220 M NaCl. If the student starts with NaCl(s) and distilled water, which of the following pieces of laboratory glassware should the student use to prepare the solution with the greatest accuracy? a. 25 mL volumetric pipet b. 100 mL Erlenmeyer flask c. 100 mL graduated cylinder d. 100 mL volumetric flask

d. 100 mL volumetric flask

3.7 Solutions and Mixtures 12. The volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution is approximately a. 50.0 mL b. 60.0 mL c. 100 mL d. 110 mL e. 120 mL

d. 110 mL

3.4 Ideal Gas Law 11. A flask contains 0.25 mole of SO2(g), 0.50 mole of CH4(g), and 0.50 mole of O2(g). The total pressure of the gases in the flask is 800 mm Hg. What is the partial pressure of the SO2(g) in the flask? a. 600 mm Hg b. 250 mm Hg c. 200 mm Hg d. 160 mm Hg

d. 160 mm Hg

3.4 Ideal Gas Law 9. An equimolar mixture of N2(g) and Ar(g) is kept inside a rigid container at a constant temperature of 300 K. The initial partial pressure of Ar in the mixture is 0.75 atm. An additional amount of Ar was added to the container, enough to double the number of moles of Ar gas in the mixture. Assuming ideal behavior, what is the final pressure of the gas mixture after the addition of the Ar gas? a. 0.75 atm, because increasing the partial pressure of Ar decreases the partial pressure of N2. b. 1.13 atm, because 33% of the moles of gas are N2. c. 1.50 atm, because the number of moles of N2 d. 2.25 atm, because doubling the number of moles of Ar doubles its partial pressure.

d. 2.25 atm, because doubling the number of moles of Ar doubles its partial pressure.

3.7 Solutions and Mixtures 14. When 70.0 mL of 3.0 M Na 2CO3 is added to 30.0 mL of 1.0 M NaHCO3 the resulting concentration of Na+ is a. 2.0 M b. 2.4 M c. 4.0 M d. 4.5 M e. 7.0 M

d. 4.5 M

3.1 IMFs 4. In which of the following liquids do the intermolecular forces include dipole-dipole forces? a. F2(l) b. CH4(l) c. CF4(l) d. CH2F2(l)

d. CH2F2(l)

3.4 Ideal Gas Law 1. How do the number of molecules in 1.0 L of each of the following gases; CH 4, N2, CO2, compare at 1 atm and 25°C? a. CH4<CO2<N2 b. N2 <CO2 <CH4 c. CO2 <CH4 <N2 d. CH4 =CO2 =N2

d. CH4 =CO2 =N2

3.1 IMFs 5. In the diagram at right, which of the labeled arrows identifies hydrogen bonding in water? There is a picture for this one a. A b. B c. C d. D

d. D

3.1 IMFs 1. The diagram at right is a molecular model of a gaseous diatomic element that is just above its boiling point. Intermolecular forces between the gas molecules will cause them to condense into the liquid phase if the temperature is lowered. Which of the following best describes how the model is limited in its depiction of the phenomenon? a. It does not show how hydrogen bonds are constantly forming, breaking, and reforming, which results in a net force of attraction between the molecules. b. It does not show how the interactions between ions and the induced molecular dipoles result in a net force of attraction between the molecules. c. It does not show how the interacting permanent dipoles of the molecules result in a net force of attraction between the molecules. d. It does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction be

d. It does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.

3.1 IMFs 2. The electron cloud of HF is smaller than that of F2, however, HF has a much higher boiling point than has F2. Which of the following explains how the dispersion-force model of intermolecular attraction does not account for the unusually high boiling point of HF? HF—> boiling point is 293K F2—> boiling point is 85K a. F2 is soluble in water, whereas HF is insoluble in water. b. The F2 molecule has a greater mass than the HF molecule has. c. Liquid F2 has weak dispersion force attractions between its molecules, whereas liquid HF has strong ionic interactions between H+ and F- ions. d. Liquid F2 has weak dispersion force attractions between its molecules, whereas liquid HF has both weak dispersion force attractions and hydrogen bonding interactions between its molecules.

d. Liquid F2 has weak dispersion force attractions between its molecules, whereas liquid HF has both weak dispersion force attractions and hydrogen bonding interactions between its molecules.

3.2 Properties of Solids 4. Based on the diagram below, which of the following best helps to explain why MgO(s) is not able to conduct electricity, but MgO(l) is a good conductor of electricity? There is a picture a. MgO(s) does not contain free electrons, but MgO(l) contains free electrons that can flow. b. MgO(s) contains no water, but MgO( l) contains water that can conduct electricity. c. MgO(s) consists of separate Mg2+ ions and O2− ions, but MgO(l) contains MgO molecules that can conduct electricity. d. MgO(s) consists of separate Mg2+ ions and O2− ions held in a fixed lattice, but in MgO(l) the ions are free to move and conduct electricity.

d. MgO(s) consists of separate Mg2+ ions and O2− ions held in a fixed lattice, but in MgO(l) the ions are free to move and conduct electricity.

3.6 Ideal Gas Law 18. The ideal gas law best describes the properties of which of the following gases at 0°C and 1 atm? a. PH3 b. HBr c. SO2 d. N2

d. N2

3.6 Ideal Gas Law 20. Based on boiling points given in the table below, which of the following gases would you expect to act most like an ideal gas under similar conditions? a. NH3 b. C4H10 c. CO2 d. N2

d. N2

3.2 Properties of Solids 11. The solid could have the chemical formula: a. CaSO4 b. Pb c. C20H42 d. SiC

d. SiC

3.2 Properties of Solids 3. A student is given a sample of a pure, white crystalline substance. Which of the following would be most useful in providing data to determine if the substance is an ionic compound? a. Examining the crystals of the substance under a microscope b. Determining the density of the substance c. Testing the electrical conductivity of the crystals d. Testing the electrical conductivity of an aqueous solution of the substance

d. Testing the electrical conductivity of an aqueous solution of the substance

3.2 Properties of Solids 7. The table below provides some information about two types of steel, both of which are alloys of iron and carbon. Which of the following best helps to explain why high-carbon steel is more rigid than low-carbon steel? There is a chart a. Elemental carbon is harder than elemental iron. b. The additional carbon atoms in the alloy make the high-carbon steel less dense. c. The additional carbon atoms in the alloy increase the thermal conductivity of the high-carbon steel. d. The additional carbon atoms in the alloy make it more difficult for the iron atoms to slide past one another.

d. The additional carbon atoms in the alloy make it more difficult for the iron atoms to slide past one another.

3.5 Kinetic Molecular Theory 8. A 1.0 L sample of helium gas at 25°C and 1atm is combined with a 1.0 L sample of neon gas at 25°C and 1.0 atm. The temperature is kept constant. Which of the following statements about combining the gases is correct? a. The average speed of the helium atoms increases when the gases are combined. b. The average speed of the neon atoms increases when the gases are combined. c. The average kinetic energy of the helium atoms increases when the gases are O combined. d. The average kinetic energy of the helium atoms and neon atoms do not change when the gases are combined.

d. The average kinetic energy of the helium atoms and neon atoms do not change when the gases are combined.

3.6 Ideal Gas Law 7. A vessel contains Ar(g) at a high pressure. Which of the following statements best helps to explain why the measured pressure is significantly greater than the pressure calculated using the ideal gas law? a. The molar mass of Ar is relatively large. b. A significant number of Ar2 molecules form. c. The attractive forces among Ar atoms cause them to collide with the walls of the container with less force. d. The combined volume of the Ar atoms is too large to be negligible compared with the total volume of the container.

d. The combined volume of the Ar atoms is too large to be negligible compared with the total volume of the container.

3.6 Ideal Gas Law 12. A vessel contains Kr(g) at high pressure. Which of the following statements best helps to explain why the measured pressure is significantly greater than the pressure calculated using the ideal gas law? a. The molecular mass of Kr is relatively large b. The attractive forces among Kr atoms cause them to collide with the walls of the container with less force c. A significant number of Kr2 molecules form d. The combined volume of the Kr atoms is too large to be negligible compared with the total volume of the container

d. The combined volume of the Kr atoms is too large to be negligible compared with the total volume of the container

3.5 Kinetic Molecular Theory 9. The graph below shows the distribution of molecular speeds for four different gases at the same temperature. There is a graph What property of the different gases can be correctly ranked using information from the graph, and why? a. The densities of the gases, because as the density of a gas increases, the average speed of its molecules decreases. b. The pressures of the gases, because the pressure exerted by a gas depends on the average speed with which its molecules are moving. c. The volumes of the gases, because at a fixed temperature the volume of a gas can be calculated using the equation PV=nRT. d. The molecular masses of the gases, because the gas molecules have the same average kinetic energy and mass can be calculated using the equation KEavg = 1⁄2mv2.

d. The molecular masses of the gases, because the gas molecules have the same average kinetic energy and mass can be calculated using the equation KEavg = 1⁄2mv2.

3.4 Ideal Gas Law 7. Diagram 1 below shows equimolar samples of two gases inside a container fitted with a removable barrier placed so that each gas occupies the same volume. The barrier is carefully removed as the temperature is held constant. Diagram 2 above shows the gases soon after the barrier is removed. Which statement describes the changes to the initial pressure of each gas and the final partial pressure of each gas in the mixture and also indicates the final total pressure? There is a picture a. The partial pressure of each gas in the mixture is double its initial pressure; the final total pressure is half the sum of the initial pressures of the two gases. b. The partial pressure of each gas in the mixture is double its initial pressure; the final total pressure is twice the sum of the initial pressures of the two gases. c. The partial pressure of each gas in the mixture is half its initial pressur

d. The partial pressure of each gas in the mixture is half its initial pressure; the final total pressure is the same as the sum of the initial pressures of the two gases.

3.5 Kinetic Molecular Theory 12. Consider the table at right. The average kinetic energy of the gas molecules is: a. Greatest in A b. Greatest in B c. Greatest in C d. The same in all three containers

d. The same in all three containers

3.7 Solutions and Mixtures 5. Which of the following best explains an exothermic heat of solution. There is a picture a. The solute-solute attractions are less than the solvent-solvent attractions. b. The solute-solute attractions are greater than the solvent-solvent attractions. c. The solute-solvent coulombic attractions release more energy than the sum of the energy required to disrupt the solute-solute and solvent-solvent interactions. d. The solute-solvent coulombic attractions release less energy than the sum of the energy required to disrupt the solute-solute and solvent-solvent interactions. e. All three steps of the dissolution process must be exothermic to result in an exothermic heat of solution.

d. The solute-solvent coulombic attractions release less energy than the sum of the energy required to disrupt the solute-solute and solvent-solvent interactions.

3.5 Kinetic Molecular Theory 14. Samples of neon gas and of krypton gas, with identical numbers of moles, pressures, and volumes, are also held at the same temperature. What can be said of the neon gas particles compared to the krypton gas particles? a. They have less kinetic energy since they are lighter. b. They have more kinetic energy since they are lighter. c. They have the same kinetic energy and the same velocity. d. They have the same kinetic energy but a different velocity.

d. They have the same kinetic energy but a different velocity.

3.2 Properties of Solids 5. A certain crystalline substance that has a low melting point does not conduct electricity in solution or when melted. This substance is likely to be: a. a covalent network solid b. a metallic solid c. a polymer d. a molecular solid

d. a molecular solid

3.6 Ideal Gas Law 8. At constant temperature, the behavior of a sample of a real gas more closely approximates that of an ideal gas as its volume is increased because the a. collisions with the walls of the container become less frequent b. average molecular speed decreases c. molecules have expanded d. average distance between molecules becomes greater. e. average molecular kinetic energy decreases.

d. average distance between molecules becomes greater.

3.7 Solutions and Mixtures 1. When NaCl dissolves in water, aqueous Na + and Cl- ions result. The force of attraction that exists between Na+ and H2O is called a(n) ______ interaction. a. dipole-dipole b. ion-ion c. hydrogen-bonding d. ion-dipole

d. ion-dipole

3.2 Properties of Solids 16. The best explanation for the fact that diamond is extremely hard is that diamond crystals a. are made up of atoms that are intrinsically hard because of their electronic structures. b. consist of positive and negative ions that are strongly attracted to each other. c. are formed under extreme conditions of temperature and pressure. d. contain orbitals or bands of delocalized electrons that belong not to single atoms but to each crystal as a whole. e. are giant molecules in which each atom forms strong covalent bonds with all of its neighboring atoms.

e. are giant molecules in which each atom forms strong covalent bonds with all of its neighboring atoms.