Chemistry ch 15

  1. kinetic molecular theory of matter
    based on the idea that particles of matter are in constant motion
  2. ideal gas
    a gas that fits all assumptions of the kinetic-molecular theory of gases
  3. what is the kinetic-molecular theory of gases based on?
    an ideal gas
  4. 5 major assumptions of an ideal gas:
    • 1. gases consist of many tiny particles that are far apart (relative).
    • 2. collisions between individual gas particles or between gas particles and the side of their container are totally elastic
    • 3. particles of gases are in constant, rapid, & random motion.
    • 4. Gas particles don't attract or repel each other.
    • 5. the average KE of gas particles depends on the temperature
  5. With the same number of atoms, the volume of a gas is
    1000 times the volume of its liquid or solid
  6. Most of the volume of a gas is occupied by
    empty space
  7. What kind of densitites do gases have?
    Low- little mass per unit volume
  8. Elastic collisions
    • there is no loss in the total KE of the system
    • however, KE may be transferred from one particle to another
  9. What kind of charge do gas particles have?
  10. KE=
    KE= 1/2 mv^2
  11. KE depends only on
    • the velocity of the particle
    • (atoms/molecules of the element/compound have the same mass)
  12. As temperature increases, velocity & KE
  13. gases at the same temperature have the same
  14. smaller particles with lower masses have what velocities?
  15. large particles have what kind of velocities?
  16. pressure
    the force exerted per unit area on a surface
  17. pressue=
  18. the pressure exerted on a surface by a gas depends on the gases
    • volume
    • temperature
    • number of gas molecules
  19. atomic presure is measured using a
  20. barometer invented by
  21. units of pressure
    • 1. mm of Hg
    • 2. 1 mm of Hg = 1 torr
    • 3. At sea level O deg C, the avg atmosphere = 760 mm of Hg
    • 4. 1 atmosphere (atm) = 760 mm of Hg
    • 5. 1 atm = 101.3 kPa
  22. 1 mm Hg =
    1 torr
  23. avg atmospheric pressure at sea level
    760 mm of Hg
  24. 1 atm=
    760 mm Hg
  25. 1 atm=
    101.3 kPa
  26. gases are most commonly measure at
    standard temperature and pressure (STP)
  27. At STP,
    • temperature= 0 deg C
    • pressure of 1 atm/101.3 kPa
  28. What is used to measure air pressure?
  29. Open manometer
    air pressure pushes down on the column of Hg while the gas in the globe tries to push the Hg up
  30. closed manometer is another name for a
  31. In a closed manometer,
    the tube isn't open and the area above the Hg is a vacuum, independant of atmospheric pressure
  32. particles of different substances at the same temperature have the same
  33. what moves faster, smaller or larger particles?
  34. Absolute zero
    • the temperature of a substance is lowered as far as it can be, and all motion ceases
    • -237 deg C
  35. 0 kelvin =
    absolute zero
  36. kelvin=
    deg C + 273
  37. deg C=
  38. temperature can also be used to determine
    the direction of the flow of energy
  39. energy flows from what to what?
    warmer objects to colder ones
  40. heat
    the amount of energy transferred between 2 objects at different temperatures. Measured in joules
  41. q=
    m x T x Cp
  42. the 4 states of matter
    • solid
    • liquid
    • gas
    • plasma
  43. States of matter: gas
    • particles are independant of each other
    • far apart
    • move in straight lines until they collide
    • assume they shape and volume of their container
  44. States of matter: liquid
    • particles are much closer than gas's
    • far enough apart to slide past each other (flow)
    • have definate volume, but take the shape of their container
    • particles have vibratory motion around ever-changing points
  45. States of matter: solid
    • particles are in fixed positions relative to neighboring particles
    • fixed pattern- definite shape and volume
    • particles have vibratory motion around a fixed point
  46. States of matter: plasma
    • occurs when matter is heated to 5,000 deg C
    • particles collide so violently that electrons are knocked off and these electrons and the positive ions that remain form plasma
  47. what do ionic compounds tend to be? why?
    • crystalline solids
    • very strong electrostatic forces holding the ions together
  48. molecular compounds are held together by
    van der Waals forces
  49. if moleculare mass is high, the compiunds tends to be a
  50. nonpolar molecules of low molecular masses tend to be
    • gases
    • HONClBrIF (except Br- liquid)
    • CO2
  51. compiunds with high molecular mass and greaty polarity tend to be
    • solids or liquids
    • H2O
Card Set
Chemistry ch 15
physical properties of gases