Systems and Processes Flashcards
[Mnemonic]
When I’m under pressure and feeling dense, all I want to do is watch TV and get HUGS.
(how to remember the eight state functions)
When I’m under pressure and feeling dense, all I want to do is watch TV and get HUGS.
- pressure (P)
- density (ρ)
- temperature (T)
- volume (v)
- enthalphy (h)
- internal energy (U)
- Gibbs free energy (G)
- entropy (S)
What are the standard conditions?
- 25°C (298 K)
- 1 atm pressure
- 1 M concentrations
Systems are defined based on mass and energy exchange with their surroundings. What are the three categories of systems?
- open (exchanges matter AND energy)
- closed (exchanges energy)
- isolated (NO exchange)
In thermodynamics, what is the difference between a system and its surroundings?
system: what is being observed
surroundings: everything else
The boundary between the two is not permanently fixed and can be moved.
What are the four types of thermodynamic processes represented on a PV diagram?
- isobaric
- isothermal
- isovolumetric
- adiabatic
“iso” means constant
When does an isobaric process occur? Isothermal? Isovolumetric?
isobaric: pressure of a system is constant
isothermal: temperature of a system is constant
isovolumetrics: volume of a system is constant
When does an adiabatic process occur?
When NO heat is exchanged between the system and the surrroundings.
What is the first law of thermodynamics?
For the first law of thermodynamics equation ΔU = Q - W. Work can have a positive value or a negative value. When is work positive?
When work is done ON the system (i.e. compression).
(piston is moved down)
For the first law of thermodynamics equation ΔU = Q - W. Work can have a positive value or a negative value. When is work negative?
When work is done BY the system (i.e. expansion).
(piston is pushed up)
