Chapter 12: States of Matter Flashcards
Properties Of Gases
- Expand to fill container
- Are highly compressible
- Have very low densities
Kinetic-Molecular Theory (KMT)
Used to explain gas behavior
1. Gas molecules are in constant, random, straight-line motion
2. Gases are mostly empty space
3. Collisions with gas molecules are elastic
4. The motion of gas molecules is proportional to Kelvin Temperature
Diffusion
The spread of one substance throughout a space or throughout a 2nd substance
Effusion
The escape of gas molecules through a tiny hole into an evacuated space
Graham’s Law
Large molecules effuse more slowly than small molecules
Pressure (P)
Force (F)/Area (A); exerted through collisions between molecules
Atmospheric Pressure
Weight of air per unit of area
Collision Increase When…
- Lower volume, same # of molecules
- Same volume, more molecules
- Higher temperature
Standard Pressure
760 mmHg = 101.3 kPa = 1.0 atm
Pascal
1 Newton/(m^2)
Manometer
Used to measure difference in pressure between atmospheric pressure and gas in a valve; Pgas = Patm + Ph
Forces Of Attraction
Intramolecular - hold atoms to atoms in compounds (covalent, ionic, metallic) - strong
Intermolecular - hold molecules to molecules - allows for states of matter to exist - weaker (dipole-dipole, london dispersion, hydrogen)
Dipole-Dipole Attraction
Molecules with permanent dipoles attracted to each other - + end to negative end - more polar = higher boiling point
London Dispersion Forces
Temporary weak dipoles found in all matter, most pronounced in high pressure and low temperature, when atoms are close electrons may line up and cause atom to become polar, molecules are long/skinny vs short/fat, strength increases with molecular weight, larger electron clouds easier to polarize
Hydrogen Bonding
Extreme dipole-dipole when hydrogen is attached to fluorine, oxygen, nitrogen; hydrogen called a naked proton as little electrons, very positive other side very negative, due to electronegativity from oxygen, fluorine, or nitrogen/why ice sinks
Dalton’s Law Of Partial Pressure
Ptot=P1+P2+P3+P4+…
P1= X1 * Ptot
X1= moles A/total moles
Viscosity
Resistance of a liquid to flow; related to ease with which molecules can move past each other; increased IMF = increased viscosity; increased temp = decreased viscosity
Surface Tension
Results from the net inward force experienced by the molecules on the surface of a liquid; increased IMF = increased surface tension
Capillary Action
The ability of a liquid to move through tiny spaces or channels in a solid material
Amorphous Solids
No crystalline structure; no definite melting point
Crystalline Solids
Definite crystalline structure; definite melting point
Metallic Solids
No crystalline structure; definite melting point
Exothermic
Releases energy (freezing, deposition, condensation)
Endothermic
Absorbs energy (melting, evaporation/boiling, sublimation)
Vapor
Gas that coexists with solid or liquid phase
Equilibrium Vapor Pressure
Pressure exerted by a vapor when evaporation = condensation
Vapor Pressure Relations
Increased temp = increased vapor pressure; increased IMF = decreased vapor pressure; boiling occurs when vapor pressure > or = atmospheric pressure
Phase Diagram
Temperature x-axis, Pressure y-axis; Solid @ left; Liquid @ top; Vapor @ bottom
Triple Point
Point where all three phases exist in equilibrium
Vapor Pressure Curves
Boils when line passes atmospheric pressure
Heating & Cooling Curves
No temp changes during phases changes
