13.1 - The Nature of Gases
2 TYPES OF ENERGY
potential - stored energy; EX food, logs, gas
kinetic
energy of movement
kinetic theory - all matter consists of tiny particles that are in constant motion
high temp - fast KE
low temp - slow KE
APPLIES TO GASES
small hard spheres without volume
particles are far apart - lots of distance and space between the particles when compared to a liquid or a solid
not attractive or repulsive forces between atoms and molecules
no definite shape or volume
motion of one particle is independent to all other particles
motion of gas particles are rapid, random, and constant
can fill any container regardless of shape or volume
particles travel in straight line paths until they collide - these collisions are perfectly elastic (the KE is transferred from 1 particle to another with out loss of KE; total KE remains constant)
gas pressure - results from the force exerted by a gas per unit surface area of an object
exert a force when they collide with each other in the container they are confined in
result of simultaneous collisions of billions of rapidly moving particles in a gas with an object
vacuum - empty space with no particles and no pressure
atmospheric pressure - a result from collisions of atom and molecules in the air with objects; drops as altitude increases
barometer - measures atm pressure
Hg barometer
high pressure, high mercury level in tube
low pressure, low mercury level in tube
Pascal (Pa) - SI unit of pressure
1 standard atm - pressure required to support 760 mm of Hg in a mercury barometer at 25C
1 atm = 760 mm Hg = 101.3 kPa
low temp, low KE - high % of molecules
high temp, high KE - low % of molecules
absolute zero (0K or -273.15C) is the temp at which the motion of particles theoretically cease/no KE
the K temp of a substance is directly proportional to the average KE of the particles of the substance
13.2 - Nature of Liquids
APPLIES TO LIQUIDS
particles are close together
attraction between atoms and molecules
definite volume
takes shape of its container
more dense than gases
barely affected by high pressure
vaporization - liquid → gas
evaporation - escape of liquid H2O molecules to a gas state without boiling
only the molecules with a certain minimum KE can escape from the surface of the liquid
a cooling process
high temp, high KE, high number of molecules that transition from a liquid to a gas
vapor pressure - measure of force exerted by a gas above a liquid
physical characteristic
condensation - gas to liquid
manometer - u shaped tool that measures vapor pressure
dynamic equilibrium - when rate of evaporation is equal to rate of condensation; constant vapor pressure
boiling point - temp at which vapor pressure of the liquid is just equal to the external pressure on the liquid
normal boiling point - bp of a liquid at 101.3 kPa
13.3 - Nature of Solids
APPLIES TO SOLIDS
tightly packed particles
dense, not easily compressed
do not flow
melting - solids to liquid
freezing - liquid to solid
melting point - temp at which a solid changes to a liquid
crystal - particles arranged an an orderly, repeating, 3D pattern → forms a crystal lattice
unit cell - smallest group of particles within a crystal that retains the geometric shape of the crystal
high mp - strong intermolecular bonds
low mp - weaker intermolecular bonds
allotropes - 2 or more different molecular forms of the same element in a physical state
carbon, phosphorus, sulfur, oxygen, boron, antimony
amorphous solid
random arrangement
lacks an ordered internal structure
EX plastic, glass (transparent fusion product of inorganic substances that have cooled to a rigid state without crystallizing)
crystalline solid
orderly
EX salts
13.4 - changes of state
sublimation - change of a substance from a solid to a vapor without passing through the liquid phase
occurs in solids with vapor pressures that exceed atm pressure at/near room temp
EX solid air fresheners
phase diagram - a graph where the relationships among the different phases of a substance in a sealed container can be represented
triple point - point on a phase diagram where all 3 curves meet