gases Flashcards
macroscopic level of gases
properties
molecular level of gases
- structure
- dynamics (motion)
- intermolecular forces
equation and definition for pressure
P=F/A
= force exerted per area
SI units for pressure
Pa = N/m^2
kPa=10^3 Pa
1atm =
101.3 kPa, 760mmHg (Torr)
1 bar =
100.0 kPa
equation for pressure with density, g, and h
p x h x g, where g = 9.8m/s^2
what does the manometer lead to?
an equalisation of pressure:
P(atm) = P(Hg) = p(Hg)gh(Hg)
if the Hg in a manometer was replaced with water, would the height of the water be greater or less than Hg?
greater, due to water’s lower density (P constant, p goes down, g constant, so h goes up)
describe kinetic molecular theory - the ideal gas
- gases made of tiny particles moving completely randomly
- total volume of particles very small compared to size of container
- particles do not interact with each other
- particle collisions are elastic (no energy lost)
- kinetic energy (KE) increases with temperature
describe (5) KE increases with temperature
for a large collection of molecules:
- at a given temperature, all gases have the same distribution of kinetic energy
- each molecule: KE = 1/2mv^2
what is the effect of temperature on average kinetic energy?
the average kinetic energy increases with temperature
state 2 equations relating kinetic energy with temperature
KE(avg) = 3RT/2
Temperature is in Kelvin
KE is in J/mol
KE (avg) = 3RT/2Na
for a single gas molecule
units for R
J/molK