Chapter 7 - Ideal Gases Flashcards
Define one mole? (3)
One mole of any substance is the amount of that substance which contains the same number of particles as there are in 0.012kg of carbon-12.
Also:
- relative atomic mass of that substance in grams.
- a mole contains a standard number of particles - Avogadro constant = 6.02x10^23 per mole
Define Boyle’s Law?
The pressure exerted by a fixed mass of gas is inversely proportional to its volume, provided the temperature of the gas remains constant.
Boyle’s law equation?
pV=constant
p=k x 1/V
p1V1 = p2V2
What are the 4 measurable properties of gases and two definitions?
Pressure (Pa) = force exerted normally per unit area by the gas on the walls of the container.
Temperature
Volume - measure of space occupied by the gas
Mass (kg or g)
Pressure is proportional to?
1/V
p1V1 = ?
p2V2
pV = ?
Constant
pV/T = ?
Constant
p1V1/T1 = ?
p2V2/T2
Ideal gas = ?
A gas that behaves according to the equation pV = NkT and pV = nRT.
When do gases often stop being ideal?
At extreme temperatures
For a gas consisting of N particles?
pV = NkT
k is Boltzmann constant = 1.38x10^-23 JK^-1
For a gas consisting of n moles?
pV = nRT
R is universal molar gas constant
8.31Jmol^-1K^-1
Na (Avogadro constant) = ?
R/k
Number of moles = ?
Mass(g) / molar mass (g/mol)
MTKE?
The mean translation kinetic energy of an atom (or molecule) of an ideal gas is proportional to the thermodynamic temperature.
Mean translational kinetic energy is proportional to = ?
T
MTKE = ?
(Sum of KE of atoms)/(no. of atoms)
OR
Average KE of one molecule over time
Where do monatomic and diatomic molecules get their KE from?
Monatomic - only translational KE
Diatomic - both translational and rotational KE
MTKE of ideal gas = ?
E = 1.5kT
Describe Maxwell-Boltzmann distribution? (3 points too)
Y axis - number of molecules
X axis - speed of molecules
- not symmetrical
- mean speed increases with temperature
- mean speed > most probable speed
KE is proportional to ?
T
V^2
5 assumptions for kinetic model of ideal gases?
- gas contains v. large no. of spherical particles.
- forces between particles are negligible, except during collisions.
- volume of the particles is negligible compared to the volume occupied by gas.
- most of time, particle moves in straight line at constant velocity. The time of collision with each other/walls of container is negligible compared with time between collisions.
- collisions between particles are perfectly elastic so no KE is lost.
