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70 Cards in this Set
- Front
- Back
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What does the word gas come from?
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Greek word "chaos"
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Who came up with the Kinetic Molecular Theory?
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Boltzmann and Maxwell
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Kinetic Molecular Theory
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Describes the behavior of gases in terms of particles in motion
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What assumptions does the Kinetic Molecular Theory make about gases?
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1. gas particles have small volume and have no significant attractive or repulsive forces
2. particles move in a straight line until they hit a barrier (elastic collisions) 3. KE = 1/2mv2 4. temp increases, KE increases |
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Elastic Collisions
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Kinetic energy between two particles does not change
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What are the properties of gases?
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1. expandible and compressible
2. low density - caused by huge volume between particles |
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Diffusion
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Gases will evenly mix together by random motion
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What is the rate of diffusion based on?
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Particle size, smaller particles diffuse faster
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Effusion
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Process of gas escaping through a tiny opening
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Graham's Law of Effusion and Diffusion
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Va/Vb = square root of molar mass b/molar mass a
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Gas Pressure
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P = F/A
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Barometer
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Invented by Torricelli, Instrument used to measure air pressure
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How does a barometer work?
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-If it is hot, KE is high, air molecules push down, causes mercury to rise
-If it is cold, KE energy is low, causes mercury to fall |
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Manometer
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Measures gas pressure - when gas is released in U-tube the two arms are no longer equal
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What are the units of pressure?
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1. 1 atom
2. 760 mm Hg 3. 101.325 kPa 4. 760 torr |
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Dalton's Law of Partial Pressures
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P total = P1 + P2 + P3 + ... Pn
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What are the three intermolecular forces?
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1. Dispersion forces
2. Dipole - dipole forces 3. Hydrogen bonds |
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Dispersion Forces
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Weak forces that result from temporary shifts in the density of electrons in electron clouds
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What are some characteristics of dispersion forces?
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-occur in nonpolar molecules (oxygen)
-volitle -weakest |
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Dipole - dipole forces
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Attractions between oppositely charged regions of polar molecules (strongest)
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Hydrogen bonds
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Dipole - dipole attraction that occurs between molecules containing a hydrogen atom bonded to a small, highly electronegative atom with at least one lone electron pair
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For a hydrogen bond to form what must Hydrogen be bonded to?
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1. Fluorine
2. Oxygen 3. Nitrogen |
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What are some characteristics of hydrogen bonds?
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-big electronegativity difference
-Hydrogen is very small - can get real close to bond |
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Intermolecular Force
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Holds together individual molecules and formula units
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Liquids
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Medium KE, definite volume, no definite shape, fluid - can flow
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Viscosity
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Measure of resistance of liquid to flow, determined by intermolecular force
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What are some characteristics of liquid and its viscosity?
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-The stronger that attractive force, the greater the viscosity
-Molecules with larger chains are more massive, have greater viscosity -Viscosity decreases as temperature increases |
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Surface tension
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Measure of individual pull by particles in the interior
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What are some characteristics of surface tension?
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- the stronger the attractive force, the stronger the surface tension
- soaps and detergents lower surface tension |
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Capillary Action
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In a very narrow tube - liquid will be pulled against gravity
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Cohesion
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Attractive force between identical molecules
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Adhesion
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Attractive force between different molecules
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Meniscus
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Forms because adhesive force between glass and water is greater than cohesive force between water - pulls up on either side
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How do plants transport food and H2O?
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Capillary action
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Solids
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Least KE, definite volume, definite shape, highest density, closely packed
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Crystalline solids
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atoms, ions, molecules (arranged in orderly 3D geometry)
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What do crystalline solids form?
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Crystalline lattice
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Unit Cell
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Smallest geometric 3D arrangement
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What determines the overall geometry of crystal?
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The type of unit cell
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What are the 5 categories of crystalline solids?
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1. molecular solid
2. covalent network solid 3. ionic solid 4. metallic solid 5. amorphous solid |
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Molecular Solid
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held together by depression force (dipole - dipole, hydrogen bond), volitile at room temp, poor conductors
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Covalent Network Solid
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Carbon/silicon, form allotropes, big and strong
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Ionic Solid
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Form crystalline lattice, high melting point, hard but brittle
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Metallic Solid
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Positive charge, high melting point, ductile/malleable/luster, good conductors
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Amorphous Solid
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No regular, repeating pattern, glass/rubber/plastics
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What does a phase change require?
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Energy
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Melting point
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Temperature at which forces holding solid together are broken - forms liquid
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Vaporization
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Process which liquid changes to gas
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Evaporation
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When vaporization only occurs at the surface of liquid
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Vapor Pressure
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Pressure exerted by vapor directly over liquid
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Boiling point
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Temperature at which vapor pressure is equal to atmospheric pressure
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Sublimation
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Process solid to gas without liquid
ex: dry ice |
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What are phase changes that release energy?
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Condensation, deposition
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Condensation
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Process in which vapor becomes a liquid
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Deposition
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Vapor to solid without liquid
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Freezing point
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Temperature at which liquid becomes a solid
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Phase diagram
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-graph pressure vs. temperature
-show what phase of a sub exists at various temperature and pressure |
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Triple point
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Pressure and temperature all three phases exist at once
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Critical Temperature
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Temp at which no matter what pressure, only vapor exists
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Critical Pressure
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Pressure at which no matter what temperature, only vapor exists
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Boiling point
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Temperature at which vapor pressure is equal to atmospheric pressure
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Sublimation
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Process solid to gas without liquid
ex: dry ice |
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What are phase changes that release energy?
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Condensation, deposition
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Condensation
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Process in which vapor becomes a liquid
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Deposition
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Vapor to solid without liquid
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Freezing point
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Temperature at which liquid becomes a solid
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Phase diagram
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-graph pressure vs. temperature
-show what phase of a sub exists at various temperature and pressure |
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Triple point
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Pressure and temperature all three phases exist at once
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Critical Temperature
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Temp at which no matter what pressure, only vapor exists
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Critical Pressure
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Pressure at which no matter what temperature, only vapor exists
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