UNIT 7: States of Matter – SELF-TEST

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Part I: Matching:  Match the letters in Column B with the numbers in Column A.

Column A                                           Column B

1.  boiling point                                   a.  P1 x V1 = P2 x V2

2.  evaporation                                    b.  the pressure above a liquid in a filled container caused by collisions of
             vaporized particles with the walls of the container

3.  combined gas law                          c.  the temperature at which solid turns into a liquid

4.  Dalton’s Law                                 d.  the change of state of a substance from liquid to gas below the boiling
             point

5.  melting point                                   e.  the change of a substance from a solid to a gas or vapor without
              passing through the liquid state

6.  triple point                                      ab.  P1 + P2 + P3 + … = Ptot

7.  vaporization                                    ac.  the conversion of a liquid to a gas or vapor below its boiling point

8. Ideal Gas Law                                 ad.  the temperature and pressure that describe the only conditions at
            which all three phases of a substance can exist at equilibrium with one
            another

9. Boyle’s Law                                    ae.  the pressure that results from the collisions of air molecules with        
            objects.

10. Charles’ Law                                bc.  the temperature at which  the vapor pressure equals the external, atmospheric pressure

11. sublimation                                    bd.  P x V = n x R x T

12. atmospheric pressure                    be. P1 x V1  =  P2 x V2
                                                                      T1              T2

13. vapor pressure                               cd. V1  =  V2
                                                                  T1       T2

Part II:  Multiple Choice: Choose the best answer and explain your choice in a sentence or with your math work.

  1. According to the kinetic theory, gases consist of particles that:  (a) occupy considerable volume.  (b) are close together.  (c) exert attractive and repulsive forces among themselves.  (d) move rapidly in constant random motion.

  2. At 80 K, the particles of a gas have:  (a) twice the average kinetic energy of the same particles at 40 K.  (b) half the average kinetic energy of the same particles at 40 K.  (c) one-fourth the average kinetic energy of the same particles at 20 K.  (d) none of these
     

  3. Compared with gases, liquids:  (a) consist of particles that are more strongly attracted to each other than those in gases.  (b) have more space between the particles that make them up.  (c) are much less dense than gases.  (d) have their volumes more greatly affected by increasing pressure than was the case in gases.
     

  4. Another word for evaporation is:  (a) boiling.  (b) vaporization.  (c) sublimation.     (d) condensation.
     

  5. Water could boil at 92 oC if:  (a) the external air pressure were lower.  (b) the external air pressure were higher.  (b) the pressure on the water increased.  (d) none of these
     

  6. In comparison with liquids and gases, solids generally are:  (a) more dense.  (b) more compressible.  (c) less organized.  (d) more likely to flow to fill their containers.
     

  7. The state of a molecular solid at room temperature depends on the strength of  (a) the bonds between atoms within the molecules.  (b) the bonds between the molecules themselves.  (c) the intermolecular forces between molecules.  (d) the metallic bonds between atoms.
     

  8. Which of the following would indicate the strongest intermolecular forces in a liquid?  (a) low boiling point  (b) high boiling point  (c) low viscosity  (d) heat of solidification
     

  9. Compared to intramolecular forces, the strength of intermolecular forces is              (a) substantially greater.  (b) slightly greater.  (c) slightly less.  (d) substantially less.
     

  10. The strength of induced dipole attractions  (a) increases with the size of the molecules.  (b) is greater than the other intermolecular forces.  (c) is great than intramolecular forces.  (d) is the same for all types of substances.
     

  11. In addition to hydrogen, what other atoms must be present in compounds that can hydrogen bond?  (a) oxygen  (b) nitrogen  (c) fluorine  (d) any of these
     

  12. The most important difference between solids and liquids is the (a) smaller distance between particles in a solid.  (b) ability of the particles in a solid to move freely.      (c) fixed pattern of particle arrangement in a solid.  (d) much greater density of solids.
     

  13. As you climb a mountain, atmospheric pressure:  (a) increases.  (b) decreases.          (c) remains the same.  (d) varies uniformly.
     

  14. A pressure of 2.5 atm is equivalent to:  (a) 41 kPa.  (b) 1900 mmHg.  (c) 2.5 kPa.    (d) 3.0 x 102 mm Hg.
     

  15. Absolute zero is:  (a) the temperature at which the motion of particles theoretically ceases.  (b) 0 K.  (c) a temperature that has never been produced in the laboratory.   (d) none of the above  (e) all of the above
     

  16. Increasing the volume of a given amount of gas at constant temperature causes the pressure to decrease because:  (a) the molecules are striking a larger area with the same force.  (b) there are fewer molecules.  (c) the molecules are moving more rapidly.  (d) there is more space for the molecules to move.
     

  17. A box with a volume of 22.4 L contains 1.0 mol of nitrogen and 2.0 mol of hydrogen at 0oC.  Which of the following statements is true?  (a) The total pressure in the box is 202.6 kPa.  (b) The partial pressures of N2 and H2 are equal.  (c) The total pressure is 101.3 kPa.  (d) The partial pressure of N2 is 101.3 kPa.
     

  18. The temperature of the gas in a balloon decreases:  (a) the volume increases.  (b) the pressure increases.  (c) the average kinetic energy of the gas particles decreases.      (d) All of the above are true.
     

  19. The volume of a gas is increased from 0.5 L to 4.0 L while the temperature is held constant.  The pressure of the gas:  (a) increases by 4 times.  (b) decreases by a factor of eight.  (c) increases by 8 times.  (d) increases by 2 times.

  20. Which of these changes would not cause an increase in the pressure of a gaseous system?  (a) Another gas is added to the container.  (b) Additional amounts of the same gas are added to the container.  (c) The temperature is increased.  (d) The container is made larger.

  21. At a certain temperature and pressure, 0.20 mol of CO2 has a volume of 3.1 L.  A 3.1-L sample of hydrogen at the same temperature and pressure:  (a) has a higher density.  (b) contains the same number of molecules.  (c) has the same mass.  (d) contains the same number of atoms.

Part III: True—False: Classify each of these statements as always true (AT), sometimes true (ST), ore never true (NT).

  1. Atmospheric pressure is 101.3 kPa.  ________

  2. The Kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles in that substance.  ________

  3. At any given temperature, the particles of all substances have the same average kinetic energy. ________

  4. The temperature of a boiling liquid can rise above its boiling point.  ________

  5. Water boils at 100oC.  ______

  6. The melting and freezing points of a substance are the same temperature.  ______

  7. Classify each of these statements as always true (AT), sometimes true (ST), or never true (NT).

  1. The particles in a substance at 100 K have twice the average kinetic energy of the particles in a substance at 50 K.
  2. The particles of a liquid do not have enough kinetic energy to overcome the attractive forces between them and escape.
  3. As a liquid evaporates, the particles with the highest kinetic energy escape first.
  4. In general, ionic solids have low melting points.
  5. The temperature of a mixture of ice and water will continue to rise as heat is applied.
  6. Halving the number of particles in a given volume of gas decreases the pressure by one-half, if temperature is kept constant.
  7. Reducing the volume of a container of gas by one-half has the same effect on pressure as reducing the quantity of the gas in the container by one-half, if temperature is kept constant.
  8. According to kinetic theory, the particles of an ideal gas have no volume and are not attracted to each other.
  9. A balloon with a volume of 60 L at 100 kPa pressure will expand to a volume of 120 L at a pressure of 50 kPa..
  10. Charles’ law concerns a direct proportion between volume and Kelvin temperature and can be represented on a graph as a straight line.
  11. The ideal gas law allows us to solve for the number of moles of a contained gas when P, V, and T are known.
  12. When two molecules of different mass have the same kinetic energy, the lighter body moves faster.
  13. In a mixture of Ar and CO, the Ar would diffuse at a faster rate.

 

PART IV: Questions and Problems

  1. What simple evidence demonstrates that gas particles are in motion?

  2. Liquid A has a vapor pressure of 7.37 kPa at 40oC.  Liquid B has a vapor pressure of 18.04 kPa at 40oC.  Which liquid would evaporate faster at 40oC?  Explain your answer.

  3. The boiling point of water in city A is 94oC; in city B it is 97oC.  Which city is at the higher elevation?

  4. Two beakers on a laboratory bench each contain a mixture of ice and water.  Three ice cubes are added to one beaker and 10 mL of hot water are added to the other beaker.  After thorough mixing, the contents of each beaker remain at their original temperature.  Explain.

  5. In terms of the type of intermolecular force present, explain why the smallest noble gas, helium, has a much lower boiling point than the largest noble gas, radon.

  6. Sulfur dioxide, SO2, and carbon dioxide, CO2, have similar formulas, yet the boiling point of sulfur dioxide is almost 70 degrees higher than that of carbon dioxide.  Explain.

  7. Briefly indicate the difference in the following types of solids: pure iron, quartz (SiO2), ice, magnesium oxide

  8. Interpret the phase diagram of CO2 at any given temperature and pressure, indicating what states of CO2 are present.  Discuss the significance of the solid lines on the phase diagram.

  9. A volume of 3.0 L of air is warmed from 50oC to 100oC.  What is the new volume if the pressure remains constant? (Name the gas law you use to solve this.)

  10. A mass of air occupies a volume of 5.7 L at a pressure of 52.7 kPa.  What is the new pressure if the same mass of air at the same temperature is transferred to a 2.0 L container? (Name the gas law you use to solve this.)

  11. A 5.0-L tank of O2 is at a pressure of 3.0 atm.  What volume of oxygen will be available if the oxygen is used at the normal atmospheric pressures of 1.0 atm?  (Name the gas law you use to solve this.)

  12. How many moles of a sample of CO2 has a volume of 75.0 mL at 30.0oC and 91 kPa? (Name the gas law you use to solve this.)

  13. What is the volume of a sample of O2 that has a mass of 50.0 g and is under a pressure of 120 kPa at 27.0oC? (Name the gas law you use to solve this.)

  14. A sample of gas occupies a volume of 80 mL at a pressure of 0.50 atm and a temperature of 0oC.  What will be its volume at a pressure of 1.50 atm and a temperature of 50oC?

  15. Determine the total pressure of a gas mixture that contains CO, Ne, and He if the partial pressures of the gases are PCO = 155 kPa, PNe = 83 kPa, and PHe = 34 kPa.

  16. What is the density of chlorine gas, Cl2, when it is pressurized to 95.0 kPa at 18oC?

  17. State and briefly explain two differences between a real and ideal gas?  Under what conditions are the ideal gas assumptions “good assumptions?"

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