Unit 7 Flashcards
atmospheric pressure
- results from the mass of the air being pulled toward the center of the earth by gravity - in other words, it results from the weight of the air
- it varies with altitude (less air is pushing down at high altitude)
standard atmosphere =
- 760 mmHg (millimeter of mercury)
- 760 torr
- 101,325 Pa (pascal)
- 29.92 in Hg
- lb/in 2
pressure=…..
force/area
Boyle’s Law
- an INVERSE relationship between pressure and volume (pressure goes up, volume goes down)
- PV= k [k is a constant] or
Charles’s Law
-volume of a gas at constant pressure increases linearly with the temperature of the gas (temperature is heated, the volume is greater)
-the volume of each gas is DIRECTLY proportional to temperature and extrapolates to zero when the temperature is 0 K
-V= Tb [T is kelvins, b is proportionally constant]
or V/T
Avogadro’s Law
- for a gas at constant temperature and pressure, the volume is DIRECTLY proportional to the number of moles of gas (volume decreases, fewer molecules)
- V=an [V is the volume of gas, n is the number of moles of gas particles, a is a proportionality constant]
or V/n
K = ….
C + 273
Ideal gas law
-Pv=nRT
-equation of state for a gas, where the state of the gas is its condition at a given time
-it is based on experimental measurements of the properties of gases
-it applies best at pressures smaller than 1 atm
-when you are dealing with changes in states in a problem, you place the variables that change on one side of the equal sign and the constants on the other
IN KELVIN and ML and KPA
A state of gas
described by its pressure, volume, temperature, and number of moles
Dalton’s Law of Partial Pressures
- For a mixture of gases in a container, the total pressure exerted is the sum of the pressures that each gas would exert if it were alone
- WHEN YOU ARE DEALING WITH MIXTURE OF GASES, THE NUMBER OF MOLE PARTICLES MATTERS, INSTEAD OF IDENTITY OR COMPOSITION OF THE INVOLVED PARTICLES
partial pressure
the pressure that a particular gas would exert if it were alone in the container
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
-the mole fraction of each component in a mixture of ideal gases is directly related to its partial pressure —> X1 =n1/nTOTAL =P1/PTOTAL
the partial pressure of a particular component of gaseous mixture is the mole fraction of that component times the total pressure (P1=X1 PTOTAL)
kinetic molecular theory (KMT)
- 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 collisions of the particles with the walls of the container are the cause of the pressure exerted by the gas.
- THe particles are assumed to exert no forces on each other; they are assumed neither to attract nor to 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.
- real gases do not conform to these assumptions
- these postulates explain ideal gas behavior
molar volume
liter/mols
22.4 liters/mol
Pressure and Volume (Boyle’s Law)
- volume goes down, pressure does up
- if there is a decrease in volume, the gas particles will hit it more often, creating more pressure
-PV= k [k is a constant]
