Exam 3 Flashcards
Pressure
Force/unit area or ma/area or P=dh*g
1atm
=760mmHg=760torr=1.01*10^5pascals
atmospheric presure
Gas molecules exert presure on their surroundings
barometer
measures atmospheric pressure; a long tube is filled with mercury and turned upside down a dish filled with mercury. The height difference or the height of how much mercury is in the tube is the atmospheric pressure.
Outside pressure pushing liquid up the tube.
manometer
is another pressure measuring device used to measure pressures close to atmospheric pressure.
open tube manometer
there is mercury in the tube between gas and atmospheric pressure.
When gas in the tube pushes harder, Pgas>patm, Pgas=patm+∆h
When the atmospheric pressure pushes harder on the mercury in the tube than the gas pressure, Pgas<Patm, Pgas=patm-∆h
2 gases, densities given
dhg=dhg; solve for height. then use +or-∆H equation
Ideal gas behavior when
1) low external pressure 2) high temperature
Boyle’s law
PV=PV
Charle’s Law
V/T=V/T
Amonton’s Law
P/T=P/T
Avogadro’s Law
V/n=V/n
General gas law
PV/T=PV/T
Gas law inverse/directly proportional
Variables on same side=inversely proportional; opposite sides=directly proportional
Gases are said to mix
no reaction
ideal gas law
PV=NRT
Ideal gas law variables
pressure in atm, v in liters, R=0.0821, T in K (C+273)
rewrite ideal gas law for density and molar mass
d=m/v=P(MM)/RT; MM=dRT/P
P and T are constant
V is directly proportional to moles.
V and T are constant
P is directly proportional to moles.
STP
273K and 1atm
1 mole of gas at STP
22.4 Liters.
Partial pressure
mole fraction*P total. mole fraction moles of gas/total moles of the entire gas
Collecting gas over water
Ptotal=Pgas+Pvp of H20
Effusion
ability of moleculues to flow from a container through a hole to teh outside world or into another container
Gas weight effusion
heavier the gas, the slower the effusion rate; the lighter the gas, the faster the effusion rate.
Heavy gas-more time
lighter gas-less time
Graham’s law
rate of effusion of gas2/rate of effusion of gas1=square root of mm of gas 1/square root of mm of gas 2= time of effusion of gas 1/time of effusion of gas 2.
Kinetic molecular theory
behavior of gases at the atomic level
3 postulates of kinetic molecular theory
particles of gases separate much larger than their size (fill the room), particles in constant motion, collisions do not lose energy, total energy=kinetic energy, average kinetic energy is dependent on temperature regardless of their molar masses.
gas is the same termperature
average ke is same for all gases.
incresing pressure
increases the average kinetic energy
kinetic energy equation
=1/2m*u^2
m=mass in kilograms
u=speed or velocity in m/s
root mean square speed/velocity or rms
rms velocity= square root of (3RT/MM)
Van Der Waals equation
for real gases
correction for intermolecular forces
observed gas pressure should be less than the gas pressure predicted. Moleculues in the gas help lessen the force of the gas.
correction for molecular volume
finite sizes; the highest value for b should be molecules that are the largest molecules
At high external pressures
PV/RT lower than ideal-intermolecular attraction; higher values due to molecular volume.
Heat of fusion
energy needed by a substance to transfer from solid state to liquid phase. melting
fusion=
-freeze (liquid state to solid)
heat of vaporization
liquid to gas state energy. boiling
vap=
-condense. gas to a liquid state.
solid to liquid to gas
heat is absorbed or gained.
gas to liquid to solid
heat is liberated or released.
temperature change/diagonal line
q=mc∆T
phase change, horizontal line
q=m∆h here m is moles or mass
Triple point
s, l, g coexist
critical point
g and l phases are indistinguishable; also supercritical fluid
if the slope of the line between the liquid and solid phase is leaning toward the liquid,
solid has a higher density
if the line is leaning toward the solid
solid has a lower density than the liquid.
line that creates the equilibrium between the liquid and gas phase
ccreated by the clausius-clapeyron equation
normal melting point
point where a solid melts at 1.0 atm
normal boiling point
liquid boils at 1.0atm
normal sublimation point
where a solid sublimes at 1.0 atm
if the pressure at the triple point is > 1.0 atm
then the substance does not have a not have a normal boiling point or a normal melting point; it does have a normal sublimation point
Vapor pressure
amount of pressure in a sealed container that is helping a solution, a liquid or a solid, turn into the gas phase
point on the solid-liquid equilibrium line
point where hte liquid is boiling. the bapor pressure of liquid=pressure of the gas.
Clausius-claperyron equation
explains curve of the liquid/gas equilibrium.
On formula sheet. t must be in kelvin. ∆Hvap in KJ and R (8.314–gas lawconstant with energy) is in J, so convert.
forces in order of strength
ion/ion, hydrogen bonding, dipole/dipole, london/dispersion
h bonding
NOF
increase the IMF, increase
increase the BP, FP/MP and ∆H
same IMF’s for covalent
higher the molar mass, higher the BP, FP, and∆H
also the more linear it is.
same IMF’s for solid ionics,
higher the charge, the greater hte IMF. same charge, the smaller anion has the stronger imf.
stronger the IMF, surface tension
surface tension is greater
water molecules
4 h bonds with neighbors. accounts for high surface tension, high capillarity and high heat of vaporization.
surface tension
energy to increase the surface areaa by a unit amount
capillary action
ability of a liquid to rise or fall in a container
cohesive forces
hold liquids together
adhesive forces
forces between liquid and a solid surface.
higher viscosity
stronger attracted moleculue with the longest chain. resistance of liquids to flow
vapor pressure
depends on Temperature.
higher the VP
the lower the BP
polarization
process of inducing a dipole
polarizability
relative tendency of a charge distribution to be distored from its normal shape by an external electric field
higher the molar mass
the greater the polarizaibility
same molar mass
more e-, then more polarizability.
