1. Kinetic theory and Ideal gases Flashcards
Assumptions for ideal gases
- A random distribution of energy between particles
- The particles behave as perfectly elastic spheres
- The volume of each molecule is negligible compared to the volume of the container
- There are no intermolecular forces
Pressure equation
pressure = force / area
total mass of a gas equation
number of moles x molar mass (Nm)
Density equation
mass / volume
Pressure of a gas equation
1/3 x NM/v x c²
1/3 x density x c²
rms speed
root mean square speed
number of moles equation
number in room / avagadros constant
total mass / molar mass
molar mass
relative molecular mass / 1000
Unit of temperature
Kelvin = +273 *C
Boyles law
pressure is equal to the inverse of volume when temperature is constant
Charles law
volume is proportional to temperature for a fixed mass and constant pressure
Pressure law or Gay -lussac Law
Pressure is directly proportional to temperature for a constant volume
Ideal gas equation
pV = nRT
Changes in gas equations
p1V1 / n1T1 = p2V2 / n2T2
Total energy in a gas
1.5 x n x R x T (R= 8.31)
or
1.5 x n x k x T (k= 1.38x10^-23)
internal energy definition
the combination of both kinetic energy of all of the particles and all the potential energy of particles
Temperature defintion
measure of the average kinetic energy of all the particles in a substance
Heat defintion
the energy transferred from a hot object to a cold object
zeroth law of thermo
if two systems are in equilibrium with a third system then they are all in equilibrium with each other
first law of thermo
the change in the internal energy of a system is equal to the heat supplied to the system minus the work done to the system
first law equation
change in U = Q - W
work done by a gas equation
W = pressure x change in volume
if change in volume is positive …
the gas is expanding and doing work
Work is done by the gas itself
if change in volume is negative …
the gas is contracting and work is being done to it
when Q is positive
heat flows into the system
when Q is negative
heat flows out of the system
what is the area under a pressure volume graph
work done
when volume increases and pressure is constant
temperature must also increase as work is done by the gas
when pressure decrease and volume is constant
work done = 0
temperature decreased
when volume decreases and pressure is constant
work is done on the gas
temperature decreases
When pressure increases and volume is constant
Work done = 0
temperature must increase
if the thermodynamic cycle is closed then…
the change in internal energy = 0
so net work done = net heat flow
Definition of a gas
The state of a substance which expands to fill any volume
What are the steps to derive the ideal gas law equation
Calculate:
1. Momentum
2. Time
3. Force
4. Pressure
5. Mean square speed
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