Matter:
States of Matter (Gas)
3 States of Matter
1.
2.
3.
4.
Solid
Liquid
Gas
Plasma ***
http://www.chem.purdue.edu/gchelp/liquids/character.html
http://www.pbs.org/wgbh/nova/physics/states-of-matter.html
http://www.middleschoolchemistry.com/multimedia/chapter2/lesson5
Gas
• Takes the shape and volume of the
container
• Easily compressed
Gas Vs. Vapor
• Gas and vapor are often used
interchangeably, but there is
a difference!!
Gas Vs. Vapor
• Gas
• Substances that exist in the
gaseous state at room
temperature.
• Vapor
• A substance that is currently a
gas, but normally is a liquid or solid
at room temperature.
Gas Vs. Vapor
• Which is correct: “water gas”, or
“water vapor”?
Gas
• Kinetic refers to motion
• Kinetic energy - energy an object
has because of it’s motion
• Kinetic theory - tiny particles in all
forms of matter are in constant
motion!
Gas
#1. Gas is composed of particles
• Small, hard spheres
• Insignificant volume; far apart from each other
#2. Particles in a gas move rapidly in constant
random motion
#3. Collisions are perfectly elastic- meaning
K.E. is transferred without loss from one
particle to another
•
Kinetic Energy and
Temperature
Kinetic Energy is related to temperature.
The faster something is moving, the
higher the temperature, the higher the
K.E. that particle has.
• Please rate the following from least to
greatest amount of K.E.
• Steam
• Water
• Ice
Pressure
• Gas Pressure – Force (F) of a gas
per unit surface area
–Due to:
• F of collisions
• # of collisions
–No particles present = no collisions
no pressure (a.k.a. vacuum)
Pressure
• Atmospheric pressure results from
the collisions of air molecules with
objects
–↓as you climb a mountain because
the air layer thins out as elevation
increases
Pressure
• The SI unit of pressure is the
pascal (Pa)
–Other units:
• kPa
• mm Hg
• atmospheres (atm)