Gases Flashcards
Properties of Gases
- Highly compressible (Boyle’s law) P1V1=P2V2
- Thermally expandable (Charle’s Law)
V1/T1=V2/T2 - Low viscosity and density
- Infinitely miscible
- Vole of gas is proportional to moles
V1/n1=V2/n2
Ideal Gas Law
Combination of Simple Gas Laws
Provided on Data sheet
V = nRT / p
pV = nRT
Viscosity
Resistance to flow
Molar Volume
The volume of an ideal gas under 273.15 K and 1 atm pressure aka STP
22.4 L at STP is one mole of gas
Why does ideal gas law or kinetic molecular theory fell?
Real gases have volume
Interparticle forces (attraction and repulsion between particles)
Low temperature or high pressure
States and IPF
Gas: no IPF
Liquid: random IPF
Solid; IPF Pattern
Sublimation
Solid to gas
Fusion
Solid to liquid
Deposition
Gas to solid
Phase Change and Energy
S-l-g means energy absorption (endothermic)
g-l-s means energy released (exothermic)
Change in H trends w/ IPF and Phase Changes
DeltaH for vaporization is stronger than DeltaH for fusion because vaporization has to break all IPF while fusion only has to break some.
Triple Point
On phase diagrams when all 3 phases coexist
Liquid-Gas Equilibria
When the rate of vaporization matches the rate of condensation at a dynamic equilibrium as long as pressure is constant
Vapor Pressure
A constant pressure of gas in a closed container in Liquid-Gas Equilibrium that depends only on the type of liquid and temperature, not the amount of liquid.
NEEDS a liquid
Vapor Pressure IPF trend
Higher IPF means lower VP because molecule wants to stay a liquid
Temperature and Vapor Pressure trend
Greater the temperature, greater the VP
Normal Boiling Point
The temperature at which the vapor pressure is 1 ATM
Solid-Liquid Equilibria
Equilibrium between solids and liquids. 0 degrees celsius
Aka melting point
Not affected by pressure
Solid-Gas Equilibrium
Point of sublimation when IPF are too week to keep particles together.
Supercritical Fluids
The boundary where phases will disappear between gasses and liquids when a closed container of liquid is heated and the density of liquids when a decreases and density of gas will decrease until both densities are EQUAL
Ion-Dipole IPF
between ions and polar molecules because of partial negative charges
Dipole-Dipole IPF
Occurs between polar dipoles aligned to maximize attractions
Hydrogen Bonding IPF
Special kind of dipole-dipole force that may occur between molecules and H atom in some, highly electronegative atom (N, O, F) and needs a lone pair
Induced Dipoles
Attractions between nonpolar molecules where an induced dipole could form from momentarily shifts in electron density
Aka instantaneous dipole
Ion-induced Dipole Forces
Between ions and nonpolar molecules. Ex) Fe 2+ in hemoglobin
Dipole-induced dipole forces
Between polar and nonpolar molecules
Ex) O2 gas and water
Instantaneous dipole-induced dipole
Between nonpolar molecules or single atoms
Polarizability
The ease with which the electron cloud can be distorted to create a charge separation
Increases with greater number of electrons and a larger molecule size
Polarizability Atom Trends
Increases down a group because the elements become bigger
Decreases across a period as the electrons are held more tightly
Polarizability Ion Trends
Anions are more polarizable than cations
