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Kinetic Theory. - explains the effects of temperature and pressure on matter. Kinetic Theory. 1.) All matter is composed of small particles. 2.) These particles are in constant motion. Kinetic Theory.
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Kinetic Theory • - explains the effects of temperature and pressure on matter.
Kinetic Theory • 1.) All matter is composed of small particles. • 2.) These particles are in constant motion.
Kinetic Theory • 3.) Collisions between particles are perfectly elastic (no change in total kinetic energy of the system).
Kinetic Theory • Mean free path - describes the average distance a molecule will travel before colliding with another molecule.
Kinetic Theory • For oxygen molecules at 25 degrees Celsius: • The mean free path is 106nm • Average speed is 1700 km/h
Kinetic Theory • For oxygen molecules at 25 degrees Celsius: • Thus, each molecule will average 4.5 billion collisions per second.
Kinetic Theory • Which factors might effect the number of particle collisions per second? (What might increase or decrease particle collisions?)
Kinetic Theory • 1.) Temperature • 2.) The number of particles in a given volume • 3.) The mass of the involved particles.
Pressure • -Created by the force and the number of gas molecule collisions on a container wall. • What is the relationship of volume and pressure?
Pressure • Pascal: the SI unit of pressure. 1 Pa = 1 N/m2. • Standard atmospheric pressure = 101.325 kPa = 1.000 Atm = 760.0 mm Hg.
Pressure • Manometers and barometers are used to measure gas pressure.
Pressure • Manometers: open-arm vs closed. • Both make use of the pressure of the gas exerted on a column of mercury.
Pressure • Calculations for both - find the difference in the height of the mercury on each side of the U-tube. Convert that to kPa as the pressure of the gas sample.
Pressure • For closed-arm, the gas pressure equals the height change.
Pressure • For open-armed, it depends on which side the mercury is highest.
Pressure • A barometer is a closed-arm manometer used to measure atmospheric pressure.
Pressure • Practice Problems 1-4 p. 382. What do you want to know?
Physical States • Temperature - measures the average kinetic energy of particles in a system. • Not all molecules at a temperature have the same exact velocity.
Physical States • An increase in temperature represents an increase in average particle velocity. • Dynamic equilibrium
Physical States • At a given temperature, the average particle velocity is dependent on the molar mass of the substance. • Ex. CO2 vs Cl2 vs O2
Physical States • Absolute zero is the theoretical temperature at which all molecule motion stops (-273.15 degrees Celsius).
Physical States • Kelvin Temperature scale is based on starting at absolute zero and increasing using the same divisions as the Celsius scale. K = C +273
Physical States • Kinetic Theory describes energy transfer between warmer and cooler objects. How?
Physical States • States of Matter • Solid • Liquid • Gaseous • Plasma