Thermodynamics (Dr King) Flashcards
(13 cards)
Define the System
The part of the universe in which we have a special interest
Define the Surroundings
The rest of the universe, in which we make our observations
What is a Diathermic wall?
A wall that permits the passage of energy to the surroundings as heat
What is a adiabatic wall?
A wall that does Not permit the passage of energy to the surroundings
Define Heat (q)
The transfer of energy as a result of a temperature difference between the system and the surroundings.
Achieves Chaotic Motion in the surroundings
Define Work (w)
The transfer of energy that causes or utilises the uniform motion of atoms in the surroundings
Often mechanical (but may be non-mechanical, e.g. electrical work)
Give the Ideal Gas Expanision Equation when pex=constant
When the gas expands under constant external pressure
work = -pexΔV
pex=pa, ΔV=M3
Equation will be provided in exam if needed
Give the Ideal Gas Expanision Equation when pex=p
When the expansion is a isothermal reversible expansion
pex=p at all times during the reaction
work = -nRTln(V2/V1)
V1/2=inital/final volume (m3)
Equation will be provided in exam if needed
Define Internal Energy (U)
The sum of all kinetic and potential contributions to the energy of all atoms, ions and molecules in the system
The grand total energy of the system
Define the First Law of Thermodynamics
ΔU = q + w
q=energy supplied as heat, w=energy supplied as work (To the system)
Equation MUST be memorised for exam
Define reversible isothermal change
ΔU = 0
If a gas loses energy by doing work on the surroundings, this energy is restored via the transfer of heat energy from the surroundings to the system
0 = q + w
Define the Molar Heat Capacity Equation (Cp) at a constant pressure (p)
Cp = (δH/δT)p
Cₚ=J K⁻¹mol⁻¹, δH= change in molar enthalpy (for the system)
Equation MUST be memorised for exam
