In this lecture you will learn:
|States of matter on earth: summary
1. Gas: high kinetic energy: no definite
shape: volume varies radically with temperature and pressure
|Atoms have THERMAL OR KINETIC ENERGY due
to the movement of electrons. Gas has more energy per atom than liquids
which have more than solids. "Thermal Energy, or heat, is the internal
energy in substances––the vibration and movement of the atoms and molecules
within substances. "
- atoms move. Randomly. They are vibrating with kinetic energy. This is called DIFFUSION or BROWNIAN MOTION.Click HERE for a fantastic java of Brownian Movement
|Example: If you put one used sweat sock
or 1 open bottle of perfume in the corner of the room, soon you will smell
it as you walk in the door. The airborne smelly molecules diffuse across
the room. If you have a good nose, you can follow the increase in concentration
of the smelly molecules to the source. Put a spoonful of sugar into coffee
or tea without stirring. At first, you cannot taste the sugar. Later, after
the sugar has dissolved and diffused, the sugar will be evenly distributed
throughout the liquid.
- Light weight molecules pick up more energy
when they are bumped by other molecules and go further, faster.
- The molecular weight of a compound affects how fast they move and how far they will diffuse in a certain time. At any given temperature, each element and compound has a specific kinetic energy. At any given temperature, some elements/compounds are gaseous, some are liquid and some are solids. But all have kinetic energy and move, even if it is limited, like in solids.
|Phase transitions: summary
gas --> liquid = condensation: lose energy
gas <-- liquid = vaporization: requires energy
liquid --> solid = freezing or solidification: lose energy
liquid <-- solid = melting: requires energy
sublimation = solid –> gas, like dry ice
|What drives phase transitions?
Heat and pressure
FOR EXAMPLE: WATER
|"Plasma is a partially ionized gas, in which a certain proportion of electrons are free rather than being bound to an atom or molecule. The ability of the positive and negative charges to move somewhat independently makes the plasma electrically conductive so that it responds strongly to electromagnetic fields. Plasma therefore has properties quite unlike those of solids, liquids or gases and is considered to be a distinct state of matter. see plasma lamp here"||AIR: Air is made up of mostly nitrogen,
oxygen and a pinch of argon. Air (including vaporized liquids) is actually
pretty dense. The earth's gravity pulls on the molecules, and they press
down on us and everything else. This is called barometric or atmospheric
pressure. As you leave earth on your way out into space, the molecules
of air thin out to nothing. In Denver, which is 1 mile above sea
level, there are fewer air molecules on top of everyone and everything
and the pressure is less. As a result, water boils (vaporizes) at a lower
temperature, and cooking must be adjusted to the lower pressure.
- Flying is only possible because of the density of air.
- Travel in space is propulsion, not flying, no wings required!
|ACTUAL TRANSITIONS IN PHASE REQUIRE WAAAAAAY
MORE HEAT than just 1 cal/g/1oC. It is the reason that steam burns
so much worse than boiling water. Each gm of boiling water must aquaria
an additional 539 calories of heat to make the transition from boiling
79.7 (80 cal) extra to melt 1 gm of ice
|"When a substance undergoes a phase change,
evaporates, condenses, freezes, melts, etc ... the arrangement of its molecules
with INCREASING TEMPS
with DECREASING TEMPS
Discuss everything you know about the differences
between gases, liquids and solids.
What is Brownian motion? Give an example.
Fill in the blanks
LABEL THE FOLLOWING
characteristic gas liquid solid energy shape volume density
explain what is happening in the following
Why does it seem an ice cream seem to suddenly melt?
Why are steam burns worse than boiling water?
Why do atoms move?