Ch. 13

• What is the kinetic molecular theory (KMT)? Theory that matter is composed of particles in motion and that motion has consequences
• What is an ideal gas? A gas that conforms exactly to the kinetic theory of gases (KTG), except it doesn't exist
• What is the kinetic theory of gases? Gases are made up of molcules with lots of empty space between Particles move quickly - pressure is caused by this motion Collisions are completely elastic (particles bounce off of each other) There are no attractive or repulsive forces between molecules KE = 1/2 mv2
• What are properties of gases resulting from the kinetic theory of gases? expansion, fluidity, low density, compressibility, diffusion, effusion
• What is expansion and what numbers from the KTG supports it? There are no attractive or repulsive forces, so it spreads; 2, 3, 4
• What is fluidity and what numbers from the KTG supports it? Particles glide past each other (in liquids and gases, bc they're both fluids); 1, 4
• What is low density and what numbers from the KTG supports it? Gases are roughly 1/1000th the density of solids and liquids; 1, 4
• What is compressibility and what numbers from the KTG supports it? The particles can be pushed together since they were far apart; 1, 4
• What is diffusion and what numbers from the KTG supports it? Spontaneous mixing of 2 substances due to random molecular motion; 2, 3, 4
• What is effusion and what numbers from the KTG supports it? A gas spreads through a small opening between containers; 2, 3, 4
• What is gas pressure? It is the result of the simultaneous collisions of billions of rapidly moving particles in a gas with an object
• What is the formula for pressure and what does each one mean? P (pressure) = F (force) / A (area)
• What is the SI unit for force? Newtons (N) - the same as kgm/s2
• What is the SI unit for pressure? Pascal (Pa)
• Explain atmospheric pressure The atmosphere is like an ocean of gases, and we live at the bottom which has the highest pressure
• What is the atmospheric pressure at sea level? 1 kg/cm2
• What is another name for atomospheric pressure? Barometric pressure
• We are not aware of the pressure of the bottom of the atmosphere because pressure outside = pressure inside.
• How is pressure measured? With a barometer
• Air pressure varies with altitude.
• Increase in altitude = decrease in air pressure.
• A decrease in air pressure indicates an increase probablity of rain.
• What happens when air is saturated with water? The average weight of air is reduced, and the pressure that air can exert decreases
• Standard pressure 1 atmosphere (atm) = 760 mm of Hg = 760 torr = 101.3 kPa
• How do we measure gas pressure? We use a manometer
• What is the least common state of matter? why? Liquids because they have the smallest temperature range
• According to the kinetic theory, the particles in liquids are: In constant motion, closer together and lower in energy than gas particlles
• What are the properties of liquids? Definite volume but no definite shape, fluidity, relatively high density, relatively incompressible, dissolving ability, ability to diffuse, surface tension, ability to evaporate & boil, and ability to solidify
• What does this property of liquid mean: def volume, but no def shape? When a liquid is transferred from a graduated cylinder to a beaker, the shape changes, but the volume doesnt (mr. s elementary school story)
• What does this property of liquids mean: fluidity? Particles glide by each other as they are attracted, but aren't locked into place
• What does this property of liquids mean: relavtively high density? Liquids are approx 1000x as dense as gases, and close in density when compared to solids
• What does this property of liquids mean: incompressible (relatively)? since the particles in liquids are close, they are incompressible; if the water is compressed to 1000x the normal atmospheric pressure, it can be reduced in volume by only 4%
• What does this property of liquids mean: dissolving ability? Liquids can have other types of matter (gases, ions) fit in between their particles and keep them dissolved
• What does this property of liquids mean: ability to diffuse? Liquids can have molecules randomly spread throughout a sample fairly quickly
• What does this property of liquids mean: surface tension? since liquid particles are close together and attracted, the molecules on the surface can form a "skin"" and support the weight of objects such as sewing needle or water striders; this also caused liquids to form droplets (stabbing)"
• What is vaporization? A general term that describes the process of when a liquid or solid becomes a gas
• What is an example of vaporization? When liquid bromine evaporates and diffuses into the air above its surface, (and is described as evaporation ? )
• What is evaporation? A more specific term that describes when particles escape from the surface of a non-boiling liquid and enter the gas state
• What is an example of evaporation? When you put perfume on your wrists and the scent evaporates from your skin and diffuses through the air
• What is boiling? A more specific term that describes the change of a liquid to bubbles of vapor that appear throughout the liquid when the equilibrium vapor pressure of the liquid equals the atmospheric pressure