Chapter 5 Flashcards
barometer
a device to measure atmospheric pressure, invented in 1643 by an Italian scientist named Evangelista Torricelli
What does atmospheric pressure result from?
the mass of the air being pulled toward the center of the earth by gravity (the weight of the air)
What is the height of the mercury at sea level (average)?
760 mm
Atmospheric pressure also varies with…
altitude
manometer
used to measure pressure
1 atm = how much torr?
760 torr
Boyle’s Law: What is the equation for Boyle’s Law?
PV=k, where k is a constant for a given sample of air at a specific temperature (P1V1=P2V2)
Pressure and Volume have an INVERSE relationship. (T/F)
True
What is a gas that strictly obeys Boyle’s law?
an ideal gas
What law found that the volume of a gas at constant pressure increases linearly with the temperature of a gas? (opposite of an inverse relationship)
Charles’s Law
Kelvin =
degrees Celsius + 273
What is the equation for Charles’s law?
V=bT (b is a proportionality constant) –> V1/T1=V2/T2
What is 0 K called?
absolute zero, because this temperature “cannot be attained”
Avogadro’s Law
that equal volumes of gases at the same temperature and pressure contain the same number of particles
According to Avogadro’s law, for a gas at constant temperature/pressure, what is directly proportional to the number of moles of a gas?
the volume
What is the equation for Avogadro’s Law?
V=an; a is a proportionality constant–> V1/n1=V2/n2
What is R, the combined proportionality constant (the UNIVERSAL GAS CONSTANT)?
.08206 L atm / K mol
What is the equation for the ideal gas law?
PV=nRT
What is the ideal gas law an equation of for a gas?
equation of STATE for a gas
What kind of equation is the ideal gas law?
empirical equation and a limiting law
What kind of substance is an ideal gas?
a hypothetical substance
What do you separate the PV=nRT equation into? (how to separate the variables)
change variables on one side and the variables that do not change on the other side
What is the volume at 0 deg Celsius and 1 atm called?
molar volume
What are the conditions 0 deg C and 1 atm called?
STP (Standard Temperature and Pressure)
What is the molar volume of an ideal gas at STP?
22.42 L
How many moles at STP?
1.000 mol
What is the molar mass equation?
MM=dRT/P (d=density)
For a mixture of gases in a container, what is the total pressure exerted?
the sum of the pressures that each gas would exert if it were alone
What is partial pressure?
the pressure that a particular gas would exert if it were alone in the container
What is the equation for the total pressure of the mixture Ptotal?
Ptotal=ntotal (RT/V)
- Volume of the individual gas particle must not be important.
2.Forces among the particles are not important. (T/F)
True
What is a mole fraction?
The ratio of the number of moles of a given component in a mixture to the total number of moles in the mixture; is directly related to partial pressure
What is the equation for a mole fraction?
n1/ntotal
n2/ntotal=P2/Ptotal (T/F)
True
Whose law is of partial pressures?
Dalton
P1=X1 (the partial pressure) times P total (T/F)
True
Mole fraction’s units are torr. (T/F)
False; there are no units for mole fraction
vapor pressure of water
When the rate of escape=the rate of return, the number of water molecules in the vapor state remains constant; the PRESSURE of water vapor remains the same.
At pressures less than 1 atm, most gases closely approach ideal gas law behavior. (T/F)
True
kinetic molecular theory (KMT)
a simple model that explains the properties of an ideal gas
What are the postulates of the Kinetic Molecular Theory?
- The particles are so small compared with the distances between them that the volume of the individual particles can be assumed to be negligible (zero).
- The particles are in constant motion.
- The particles are assumed to exert no forces on each other; they are assumed to neither attract more repel each other.
- The average kinetic energy of a collection of gas particles is assumed to be directly proportional to the Kelvin temperature of the gas.
As V is decreased, P…
increases
As T increases, P…
increases
As T increases, V… (increases/decreases)
increases
As n increases, V…
must increase.
KMT states…
that independent particles are independent, and V is assumed to be 0. The identity of the molecule is therefore unimportant.
joule=
kg times m^2/s^2
KEavg= (1/2mv^2)
3/2RT
u(rms- the root mean square velocity)=rad(3RT/M) (T/F)
True
What is effusion?
the movement of a gas through a small opening into an evacuated container (vacuum)
Diffusion
term used to describe the mixing of gases
What is Graham’s law of effusion?
rate of effusion for gas 1/rate of effusion for gas 2= rad M2/ rad M1 (M= molar mass of gas)
DIffusion doesn’t need a more complex analysis. (T/F)
False; the ratio is less or more than; a quantitative analysis of diffusion requires a more complex analysis.
Why i shte volume available to a given particle in a real gas less than the volume of the container?
because the gas particles themselves take up some of the space
real equation for ideal gas equation
P=nRT/(V-nb) –> b is an empirical constant
observed pressure Pobs:
Pobs=(P-correction factor)=(nRT/(V-nb)- correction factor)