gases Flashcards
four gaseous properties
- moles (n)
- pressure (p)
- volume (v)
- temperature (T)
moles
- the amount of gas in a particular sample, in moles
volume
- the amount of space a gas sample occupies (the volume of its container)
- usually in L
pressure
- force exerted over an area: the frequency and force of collisions in a gaseous system btwn particles and the container
- atm, KPa, and torr
- 1 atm: 760 torr/mmHg, 101 KPa
kinetic energy (KE)
- the energy associated with the velocity of an object
temperature
- measure of the average KE of the sample
- temperature up, particles’ avg velocity up, pressure up in a rigid container/volume up in a fluid container
- measured in C, but calculate in K
- C + 273 = K
internal pressure
outward pressure on the inner walls of a container, caused by collisions between gas molecules in the sample and the walls
external pressures
inward pressure on the outer walls of the container caused by atmospheric pressure
temperature
the average kinetic energy of the center of mass of the gas sample
kinetic molecular theory
is based on the idea that matter is composed of tiny particles that are always in motion and helps explain observable properties and behaviors of gases
KMT postulate 1
gas particles move in continuous, random motion
KMT postulate 2
the volume of gas particles is negligible compared to the volume of the container
KMT postulate 3
attractive & repulsive forces between as particles are also negligible (no IMF)
KMT postulate 4
under constant temperature, there is a constant KEL perfectly elastic collisions (no energy is lost)
KMT postulate 5
the average KE of particles is proportional to the absolute temperature in K
simple gas laws
describe how 2 of the 4 gas properties are related if the other 2 are constant
pressure & volume
P1V1=P2V2
- inversely proportional
temperature & pressure
P1/T1=P2/T2
- directly proportional
temperature & volume
V1/T1=V2/T2
- directly proportional
moles & pressure
P1/N1=P2/N2
- directly proportional
moles & volume
V1/N1=V2/N2
- directly proportional
combined gas laws
(P1V1/N1T1)=(P2V2/N2T2)
- combines all proportionalities, cancels constants, more realistic
- for systems undergoing change
ideal gas laws
PV=nRT
- R=0.08206
- an ideal gas adheres to KMT’s postulates, and for an ideal gas, PV/NT=R, the constant
dalton’s law of partial pressure
total P=Pa+Pb+…
- Pa=(NaRTa)/Va, Pb…
according to KMT, the pressure of a gas depends on the pressure with the container, not other particles, so particle’s individual pressures don’t affect one another
- so each gas’s pressure can be added to find the total gas
