46 terms

# Chem Exam - Phases of Matter

I hope this is of some use to y'all. I believe I covered everything...
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kinetic molecular theory of matter
the idea that particles of matter are always in motion
Ideal Gas
an imaginary gas that perfectly fits all the assumptions of the kinetic-molecular theory
The 5 Assumptions of an Ideal Gas
1) Gases consist of large numbers of tiny particles that are far apart relative to their size
2) Collisions between gas particles and between particles and container walls are elastic energy
3) Particles are in continuous, rapid, random motion.
4) There are no forces of attraction or repulsion between gas particles
5) The average kinetic energy of gas particles depends on the temperature of the gas
Diffusion
spontaneous mixing caused by the random motion--of (gas) particles.
The 3 Conditions for the Rate of Diffusion
- Speed
- Diameter of gas particle
- Any attractive forces
Effusion
The passing of gas particles through a tiny opening
Pressure
the force per unit area
Atmosphere
the unit we generally use to measure pressure
Standard Temperature and Pressure (STP)
exactly 1 atm and zero degrees Celsius
John Dalton
He found that for pressure of gases "the total is the sum of the parts" (which is only true if there is no chemical reaction between the gases).
Dalton's Law of Partial Pressures
- Each gas in a mixture creates pressure as if the other gases were not present.
- The total pressure is the sum of the pressures created by the gases in the mixture.
Partial Pressure
the pressure each gas exerts in the mixture
Liquid
has a definite volume with a shape determined by the container
Relative Incompressibility
even at high pressures, liquids only compress a little
Viscosity
measure of the resistance of a liquid to flow
Surface Tension
force that pulls adjacent parts of a liquid's surface together, decreasing the surface area to the smallest possible size
Capillary Action
the attraction of a surface of a liquid to the surface of a solid
Meniscus
the curve in the upper surface of a standing body of liquid, produced in response to the surface of the container or another object
Vaporization
when a liquid or solid changes to a gas
Evaporation
the process during which particles escape from the surface of a non-boiling liquid and become gases
Boiling
the conversion of a liquid to a vapor--the change of a liquid to bubbles of vapor that appear throughout the liquid
Formation of solids
the KE of the particles decreases when a liquid is cooled
Freezing
the physical change of a liquid to a solid by removal of heat
Solids
Have a definite shape and definite volume
Crystalline Solids
solids with particles arranged in an orderly, geometric, repeating pattern. Such is the case for most pure minerals.
Amorphous Solids
solids with no regular, natural shape. They can flow, but do so very, very slowly (glass and plastics for example).
Melting Point
temperature at which solids change to a liquid
Metallic compounds
compounds with the highest melting points
Non-polar compounds
compounds with the lowest melting points
3 Basic Types of Crystals
- ionic
- covalent
- metallic
Unit Cell
the smallest arrangement of connected points that can be repeated in 3 directions to form the lattice
3 Common Unit Cells
- simple cubic
- body centered cubic
- face centered cubic
5 Categories of Crystalline Solids
- Atomic
- Molecular
- Covalent network
- Ionic
- Metallic
Equilibrium
dynamic condition where two opposing changes occur at equal rates in a closed system
(It is achieved when the rates of the forward and reverse reactions become equal.)
Volatile Liquids
liquids that evaporate readily (because they have weak attractive forces)
Molar Enthalpy of Vaporization
the amount of heat energy required to vaporize a mole of liquid at constant pressure
Freezing Point
the temperature at which the solid and liquid are in equilibrium at 1 atmosphere
Melting
the reverse of freezing
Molar Enthalpy of Fusion
the amount of heat energy required to melt a mole of solid at its melting point
Sublimation
when a solid goes directly into a vapor, skipping the liquid step (i.e. dry ice)
Deposition
when a vapor goes directly to a solid (i.e. frost on a windshield)
Phase Diagram
a diagram used to tell us about how the system will change with changes in P and T
Triple Point
(On the phase diagram) the T and P conditions where the solid, liquid, and gas exist in equilibrium
Critical Point
(On the phase diagram) this point indicates the critical temperature and critical pressure
Critical Temperature
the temperature above which the substance cannot exist as a liquid, irrespective of pressure
Critical Pressure
the lowest pressure at which a substance can exist as a liquid at the critical temperature