Unit 5:Gases and Intermolecular Forces Flashcards
whats the STP for gases
o degrees Celcius and 1 atm
equation for ideal gas law
PV = nRT, where R = 0.08206 L∙atm∙mol-1K-1
what are each mixture of gas considered?
We can consider each gas in a mixture separately. Each gas in a mixture has an amount (i.e. number of moles) and its own “partial pressure”.
whats the partial pressure of gas in a mixture
The partial pressure of a gas in a mixture is the pressure exerted by only that gas. The total pressure of the mixture equals the sum of all the partial pressures.
how can you describe a mixture of gases
In the same way, you can describe a mixture of gases in terms of partial pressures. If you have a mixture of oxygen that has a partial pressure of 1 atm and helium that has a partial pressure of 2 atm, the total pressure is 3 atm.
PO2 = 1 atm PHe = 2 atm Ptotal = 3 atm
how does the partial presssure of gas relate to gas inside a container (I probably worded this weird but IDK what I’m doin)
The partial pressure of a gas is the pressure that gas would exert if that amount of the gas were all alone in the container.
Dalton’s law of partial pressures
states that the total pressure in a container equals the sum of the individual pressures:
Ptotal = P1 + P2 + P3 + etc….
vapor pressure
The vapor pressure of a liquid is the pressure that the gaseous form exerts when the maximum amount of the liquid becomes a gas. The vapor pressure of water at 20 °C is 17.5 torr.
two equations to calculate humidity
humidity= 100%(amount of water in the air/the maximum amount of water that can be in the air)
humidity=100%(partial pressure
of water in the air/vapor pressure of water)
describe solids
definite volume definite shape often ordered high density atoms can vibrate
describe liquids
definite volume indefinite shape not ordered high density atoms can move
describe gases
indefinite volume indefinite shape not ordered low density atoms can move
What is P=F/A
Pressure = force divided by area
kinetic molecular theory
Gases are composed of rapidly moving particles that collide elastically. They create forces when they bump into things.
whats an ideal gas
“Ideal” gas molecules/atoms do NOT:
1) occupy any space 2) attract or repel each other
what causes air pressure
air atoms and molecules bumping into stuff
what does every variable in PV=nRT mean
p-pressure v- volume n- number of moles r- 0.082-6 T- temperature
what does every varibale in L-atm-mol^-1-k^-1 mean
l- liters
atm- atmospheric pressure
mol- moles
k- kelvin’s temp
what is STP used for
used for reference calculations
what does “like dissolve like”mean
things of one group dissolves for things of that same group
what does water dissolve
ionic compunds
things that can H-bond
hydrophillic
what does oil dissolve
non-polar covalent
things that can’t H-bond
hydrophobic
hydrophilic heads are polar or non-polar
hydrophilic heads are polar
hydrophobic heads are….
non-polar
why dont oil and water mix
grease is non-polar and clumps together
what is viscosity related to
intermolecular forces
molecular size
temperature
what causes the states of matter
temperature intermolecular forces (IMF)
temperature
Temperature is a measure of the average kinetic energy of atoms
whats the equation for KE
KE=1/2mv
how active are all matter above absolute zero
All matter above absolute zero is in motion. The higher the temperature, the faster the atoms move.
why do gas atoms fly around without sticking close to other atoms?
Gas atoms fly around without sticking close to other atoms because their kinetic energy is much larger than the intermolecular forces between them.
why does solid atoms stick together/very closely and don’t move(only vibrate)
Solid atoms stick together very closely and don’t move around (they only vibrate) because their kinetic energy is much smaller than the intermolecular forces between them.
why does liquid atoms stay close to each outher but mover around freely?
their kinetic energy is comparable to the intermolecular forces between them.
kinetic-molecular gas theory
Ideal gas molecules/atoms do NOT:
1) occupy any space 2) have any intermolecular forces
what gases are NOT ideal
1) ones with strong IMF
2) ones at low temperature
3) ones at high pressure
describe molecular solids
Molecular solids are held together only by intermolecular forces. Because intermolecular forces are weak, molecular solids are usually soft.
are ionic solids brittle or strong? Why
brittle b/c of repulsion, slight shift of the atoms
what are Dipole-Dipole forces
Polar molecules have charges much smaller than + or – 1, so dipole-dipole forces are much weaker than ion-ion forces.
how strong are dipole-dipole forces compared to ion-ion
dipole-dipole forces are much weaker than ion-ion forces.
what are 3 charactersistics of hydrogen bonding
1) NOT real bonds
2) extra strong dipole-dipole attractions
3) in molecules with N-H, O-H, F-H
instantaneous dipole moment
Because electrons are always in motion, at any instant a non-polar molecule can have an instantaneous dipole
induced dipole moment
An instantaneous dipole moment can induce a dipole moment in a nearby molecule and cause an attraction
London Dispersion
The attraction between the instantaneous dipole moment and the induced dipole moment is called London Dispersion Forces. This force exists between any type of molecule over the entire surface of the molecules!
Larger molecules = stronger London forces
name all the intramollecular forces
covalent and ionic bonds
list all the intermolecular forces
hydrogen bonds
dipole-dipole bonds
london forces
list the molecular forces in order of strongest to weakest
covalent bonds, ionic bonds, hydrogen bonds, dipole-dipole forces, london forces
supercritical fluids
Above the critical temperature and pressure, a substance is said to exist as a supercritical fluid, which like a gas has the volume of its container but can have high densities like liquids. Supercritical fluids can dissolve things (like a liquid) and effuse through solids (like a gas).
whats critical temperature
The critical temperature (TC) of a substance is the highest temperature at which a liquid can exist. Above the TC, there is no distinct transition between liquid and gas!
name the type of force attraction molecular forces have and give examples
Material:
molecular
Force of Attraction: Intermolecular forces
Ex: water, air, organic materials, wood, plastic
name the type of force attraction of metallic materals and give examples
material: metallic force of Attraction: metallic bonds Ex: iron steel, copper, bronze, mecury, sodium
name the type of force attraction ionic materials have and give examples
material: ionic
force of attraction: ionic bonds
Examples: salt, most rocks, most gems ceramics
name the type of force attraction network materials have and give examples
material: network
force of attraction: covalent
ex: diamond, graphite, boron, silicon
