Thermodynamics Flashcards
What is thermodynamics?
The study of energy and its effect on a system
What is a system?
A group of things that come together to perform a specific task
What is internal energy?
The summation of the KE and the PE of a molecule. (Random Molecular Movement Energy) given by the symbol “U”.
How is the internal energy distributed?
Randomly, meaning that any particle can have any amount of energy
What is potential energy?
The position and interactions of molecules determine Potential Energy.
The further apart the molecules are the greater their potential energy
What is the Celsius?
Determined based on the melting (0) and boiling point of water (100) in order to make a scale
What is the Kelvin?
Has the same increments as the Celsius, but isn’t based on the boiling point of water, so starts at 0
What is absolute 0?
When molecules have minimum internal energy. It is 0 Kelvin and -273.15 Celsius
What is the specific heat capacity?
The energy required to increase the temperature of 1kg of a substance by 1K
What is the formula for energy using specific heat capacity?
Energy = mass * specific heat capacity * change in temperature
ΔE = mcΔθ
What are solids?
Molecules vibrate around a fixed position
What are Liquids?
Molecules constantly freely move around but are still attracted to each other
What are gases?
Molecules move freely and randomly
What happens when you increase the temperature of a substance?
Increase kinetic energy and therefore internal energy
What happens when there is a change of state ?
kinetic energy stays the same as the energy is being transferred to the potential energy store of the molecules.
What is the specific latent heat? (fusion)(vapourisation)
The energy required to change the state of 1kg of a substance
The formula relating energy to specific latent heat?
Energy change = specific latent heat x mass of substance changed
ΔE = L*Δm
What Assumptions are made in Kinetic theory?
The motion of molecules is random
Totally elastic collisions
Molecules move in straight lines at constant speeds
Negligible intermolecular forces
The particles are all identical
Boyle’s Law?
Law linking the pressure and the volume at a CONSTANT TEMPERATURE.
As the volume decreases, pressure increases as there is an increased collision rate
P = k/V so PV = k
Charles’ Law?
Law linking the temperature and the volume at a CONSTANT PRESSURE.
V = KT As the temperature increases there should be more collisions. But pressure is kept constant so volume must increase instead
Pressure Law?
Law linking the temperature and the pressure at a CONSTANT VOLUME.
P = kT
As temperature increases, average kinetic energy increases, more collisions so more pressure
Ideal Gas equation?
PV = nRT “R” is the gas constant “n” Avagadro’s constant
PV = NkT “N” for number of molecules “k” for Boltzmann constant
PV = 1/3 Nmc^2
What is the value of the Boltzmann constant?
k = 1.38 x10-23
Gas constant?
R = 8.31
