Gen chem 8 Flashcards
what is the strength of the IF’s that exist btween gas particles? and what property does this allow them to have?
gases are easily what?
what are the four variables to define the state of a gas sample?
weak
ability to fill any volume
compressible
pressure(P), Volume(v), temperature (T), moles (n)
what two gas units are equivalent? SI unit for pressure?
conversion units btween atm, mmHg, torr and kPa?
Explain how mercury rises in a barometer
-what pressure creates a downward force on the pool of mercury at the base of barometer while the mercury in the column exerts a what force (its what) based on its density
-the what of the mercury creates a what in the top of the tube
-when the external air exerts a higher force, than the weight of the mercury in the column, the column does what?
-when the external air exerts a lower force, than the weight of the mercury in the column, the column does what?
mmHg and torr
SI unit for pressure is Pa (Pascal)
1 atm=760 mmHg=760 torr= 101.325 kPa
-atm pressure creates a downward force on the pool of mercury at the base of barometer while the mercury in the column exerts an opposing force (its weight) based on its density
-the weight of the mercury creates a vacuum in the top of the tube
-when the external air exerts a higher force, than the weight of the mercury in the column, the column rises.
-when the external air exerts a lower force, than the weight of the mercury in the column, the column falls.
many processes involving gases take place under STP(what is STP?)
STP conditions are not identical to standard state conditions, whats the difference? when is each used?
what do we always assume about gases?
what is an ideal gas? when do real gases deviate from ideal gases?
STP is 273 K (0 C)and 1 atm, used for gas law calcs
standard state conditions 298 K, 1 atm, 1 M concs), used for calcs of enthalpy, entropy, G, and electrochemical cell voltage
we always assume they are ideal; ideal gases have no IFs working on them and they have no volume; real gases deviate from ideal gases at high pressures(low volumes) and low temps
what is the ideal gas law eqn? when can R be changed?
what is density defined as? what units?
how can we rearrange the ideal gas law to find the density of any gas?
the mole of an ideal gas at STP occupies what volume?
what is the combined gas law eqn? what does this eqn assume?
derivation of the combined gas law to find changes in volume? what is V2 then used to find and what eqn?
PV=nRT; R is 8.21 x 10-2 L.atm/mol K
R(8.314 J/mol K can be changed when you u substitute pascal and cubic meters
density is defined as the mass per unit volume, expressed in g/L
-Start with the ideal gas law > PV=nRT
where n= m(mass)/M(molar mass)
Therefore, PV=m/M RT
and p= m/V = PM/RT
22.4L
combined gas law eqn = P1V1/T1//P2V2/T2; subscripts 1 and 2 refer to two states of the gas at STP and at actual temp and pressure; this eqn assumes the number of moles stay constant
to find changes in volume = V2=V1(P1/P2)x(T2/T1); V2 is then used to find the density of the gas under nonstandard conditions» p=m/V2
sometimes when the identify of a gas is unknown, what can e use to identify it?
having density, what eqn can we use to find the volume at the gas at STP? and what do we substitute for T2 and P2
then what do we use to find the density of the gas at STP? then how is molar mass calcd?
we can use molar mass to find the gas’ identity.
V2=V1(P1/P2)x(T2/T1); subbing 273 K for T2 and 1 atm for P2
we find the density of the gas at STP by dividing the sample mass by the V2; then molar mass is calcd with this eqn»> M=pSTP x 22.4 L/mol
what does avogadros principle state?
what will equal amounts of all gases at the same temp and pressure occupy?
eqn for avogadros principle?
what dos boyles law show? eqn?
it states that all gases at a constant temp and pressure occupy volumes that are directly proportional to the number of moles of gas present
- they will occupy equal volumes
- n/V=k or n1/V1=n2/V2; k is a constant and n1 and n2 are the numbers of moles of gas 1 and 2, and V1 and V2 are the volumes of the gases
boyles law shows that for a given gaseous sample held at constant temp (isothermal conditions), the volume of the gas is inversely proportional to its pressure
eqn» PV= k or P1V1=P2V2; k is a constant and the subscripts 1 and 2 rep two different sets of P and v conditions
boyles law is a special case of the ideal gas law in which n and T are constant.
what does a boyles law graph look like? another name for a boyles law graph trend?
what does charles law state? eqn?
special case of the ideal gas law?
on a charles law graph when T=0 (absolute zero) and what do we find about volume?
how does a charles law graph look and what is the trend called?
on page 268; isothermal compression
charles law states that at constant pressure, the volume of a gas is proportional to its absolute temperature, expressed in kelvins
eqn for charles law is V/T=k or V1/T1=V2/T2; k is a proportionality constant and subscripts 1 and 2 reps two different sets of temp and volume conditions
charles law is a special case of the ideal gas law in which n and P are constant
the graph is on page 269 and its called Isobaric expansion(as T goes up, V goes up)
what is the eqn for gay lussacs law?
special case?
GRAPH AND TREND?
what laws and components does the combined gas law relate?
P/T=k or P1/T1=P2/T2; k is a proportionality constant and subscripts 1 and 2 rep 2 diff sets of temp and pressure conditions
special case of the ideal gas law in which n and V are constant.
GRAPH IS ON PAGE 270; ISOVOLUMETRIC HEATING (AS TEMP INCREADES, PRESSURE INCREASES)
the combined gas law relates pressure and volume(boyles law) in the numerator, and relates the variations in temp to both volume(charles law) and pressure(gay-lussacs law) simul
when two or more gases that dont chemically interact are found in the same vessel, each gas will behave how?
the pressure exerted by each gas in the mixture will be equal to the pressure that the gas would exert if what?
define partial pressure
daltons law of partial pressures states? eqn and variables?
when two or more gases that dont chemically interact are found in the same vessel, each gas will behave independently of each other(each gas will acts as if its the only gas in the container
the pressure exerted by each gas in the mixture will be equal to the pressure that the gas would exert if it were the only one in the container
partial pressure is the pressure exerted by each indiv gas
daltons law of partial pressures states that the total pressure of a gaseous mixture is equal to the sum of the partial pressures of the indiv components; eqn and variables is on page 271
the partial pressure of a gas is related to its what fraction by what eqns? variables?
at applied pressures, the what of gas in a liquid is in increased or decreased?
define vapor pressure
what pressure from the evaporated moles forces some of the gas into the liquid phase and what is reached btween what and what(and with what eqn and variables)
mole fraction
eqns and variables on page 271
concentration
vapor pressure exerted by evaporated particles above the surface of a liquid
vapor pressure from the evaporated moles forces some of the gas into the liquid phase and equilibrium is reached btween condensation and evaporation; eqn and variables on page 272
the solubility of a gas will increase with what’ing partial pressure of a gas
under the kinetic molecular theory, there is an assumption that collisions btween any two gas particles or btween particles and the container walls are what, meaning that there is a conservation of both what and what energy
according to the kinetic molecular theory of gases, the average kinetic energy of a gas particle is proportional to the what of the gas(and eqn and variables)(and what does this eqn show)
what is one way to define an average speed of a gas particle?
increasing
under the kinetic molecular theory, there is an assumption that collisions btween any two gas particles or btween particles and the container walls are elastic, meaning that there is a conservation of both momentum and kinetic energy
-according to the kinetic molecular theory of gases, the average kinetic energy of a gas particle is proportional to the absolute temp of the gas; eqn and variables on page 276»this eqn shows that the speed of a gas particle related to its absolute temp
-one way to define an average speed of a gas particles is to determine the average kinetic energy per particle and then calculate the speed to which this corresponds; the resultant quantity known as the root mean square speed is given by the eqn on page 277
the higher the temp, how will gas particles move?
the larger the molecules, how will gas particles move?
what does a maxwell-boltzmann distrib curve show?
the movement of molecules from high to low conc in a medium (such as air or water is called)?
what does the kinetic molec theory of gases predict about how heavier and lighter gases diffuse and why?
all gas particles that have the same average kinetic energy at the what temp?
the faster they move
the slower they move
this curve shows the distrib of gas particle speeds at a given temp
diffusion
heavier gases diffuse more slowly than lighter ones becuz of their differing speeds
all gas particles that have the same average kinetic energy at the same temp
under isothermal and isobaric conditions, the rates at which two gases diffuse are what proportional to the square roots of their whats?»what eqn is this related to and what variable defs?
define effusion
under the kinetic molecular theory of gases, for two gases at the same temp, the rates of what are proportional to the average whats
difference btween diffusion and effusion; what will be the same for both questions
under isothermal and isobaric conditions, the rates at which two gases diffuse are inversely proportional to the square roots of their molar masses.
eqn and variables on page 279
effusion is the flow of gas particles under pressure from one compartment to another thru a small opening
under the kinetic molecular theory of gases, for two gases at the same temp, the rates of effusion are proportional to the average speeds
book says diffusion is when gases mix together; effusion is when a gas moves thru a small hole under pressure; both conditions will be slower for larger molecules and both use the same eqn
as the pressure of a gas goes up, what happens to the particles
as the condensation pressure for a given temp is approached, what happens to IFs until the gas does what?
at high pressure, why is a gas’ volume less than would be predicted by the ideal gas law due to what
-at high pressures what happens to the size of the particles due to the distance btween them and what does this cause the gas to do?
the particles are pushed closer and closer together
as the condensation pressure for a given temp is approached, IFs become more and more significant until the gas turns into a liquid
-at high pressures, a gas’ volume is less than would be predicted by the ideal as law becuz of intermolecular attraction
-at high pressures, the size of the particles becomes large compared to the distance btween them and this causes the gas to take up a larger volume than would be predicted by the ideal gas law
as the temp of a gas goes down, what happens to the average speed of the gas molecules
as the condensation temp is approached for a given pressure what do intermolecular attractions cause the gas to do?
like deviations due to pressure, as the temp of a gas goes down toward what point(which is the same as its boiing point), what do intermolecular attractions cause the gas to have?
as the temp of a gas goes down, the average speed of the gas molecules goes down and the attractive intermolec forces becomes significantly
as the condensation temp is approached for a given pressure, the intermolecular attractions cause the gas to condense into a liquid state
-like deviations due to pressure, as the temp of a gas is reduced towarda a condensation point(which is the same as its boiling point), intermolecular attractions causes the gas to have a smaller volume than that which would be predicted by the ideal gas law.
