Week 2 Flashcards
Define state
If a system is not undergoing any change, then all properties can be measured or calculated throughout the entire system, meaning that the system’s condition can be perfectly described. This means that we know the state of the system
True or False: At any given state, it is guaranteed that all properties of a system have fixed values
True. If one property changes, the state also changes
In ________ state, there are no unbalanced potentials within the system (experiences no changes when it is isolated from its surroundings)
Equilibrium
Define thermal equilibrium
Temperature is the same throughout the entire system
Define mechanical equilibrium
No change in pressure at any point of the system with respect to time (pressure may change due to height, but usually small and disregarded)
Define phase equilibrium
If a system involves two phases, it is in phase equilibrium when the mass of each phase reaches an equilibrium level and stays there
Define chemical equilibrium
When its chemical composition does not change with time
Define state postulate (guaranteed question on the midterm)
The state postulate can be defined as the specific number of properties sufficient to fix a state, not all properties of a state must be specified. The number of properties required to fix the state of a system is given by the state postulate
What is the state postulate of a simple compressible system
Two independent, intensive properties: Temperature and pressure (always the case for a simple compressible system)
Define process
Any change that a system undergoes from one equilibrium state to another
Define path
The series of states through which a system passes during a process
True or False: To completely describe a process, all that is needed is to specify the initial and final states of the process, the path it follows, and the interactions with the surroundings
True
When a process proceeds in a way that the system remains infinitesimally close to an equilibrium state at all times, it is called a ___________ or ____________ process
Quasi-static, quasi-equilibrium
Define quasi-static or quasi-equilibrium processes
A sufficiently slow process that allows the system to adjust itself internally so that the properties in one part of the system do not change any faster than those at other parts
True or False: An example of a quasi-equilibrium process would be a compression cylinder moving its piston extremely quickly
False, there would be pressure differences at different areas of the system if the cylinder compressed itself very quickly
What are the three “Iso-“ processes
Isothermal, Isobaric, and Isochoric/Isometric processes
Define an isothermal process
A process where temperature remains constant
Define an isobaric process
A process where pressure remains constant
Define an isochoric/isometric process
A process where volume remains constant
A system is said to have undergone a _____ if it returns to its initial state at the end of the process
Cycle
Define a steady-flow process
A process during which a fluid flows through a control volume steadily. Fluid properties can change from point to point within the control volume, but at any fixed point they remain the same during the entire process. The mass, volume, and total energy of the control volume remain constant during a steady-flow process
True or False: If the energy crossing the boundary of a closed system is not heat, it must be work
True, energy can cross the boundary of a closed system only in the form of heat or work
The work done per unit time is called _____ and is denoted as _______
Power, Watt (J/s)
Define an adiabatic system
A process in which no heat transfer takes place
True or False: A quantity that is transferred to or from a system during an interaction is a property
False, the amount of such a quantity depends on more than just the state of the system
True or False: Heat and work are energy transfer mechanisms between the system and surroundings
True
What are the four similarities between heat and work
- Both are recognized at the boundaries of a system as they cross the boundaries (i.e., both heat and work are boundary phenomena)
- Systems possess energy, but not heat or work
- Both are associated with a process, not a state. Unlike properties, heat or work has no meaning at a state
- Both are path functions (i.e., their magnitudes depend on the path followed during a process as well as the end states)
True or False: Path functions have exact differentials denoted by the symbol ‘d’
False, they have inexact differentials denoted by the symbol δ
Properties are ______ functions and have exact differentials denoted by the symbol ___
Point, ‘d’
Define intensive property
A property independent of the mass of a system (T, P)
Define extensive property
A property whose values depend on the size or extent of the system (m, V)
Define specific property
An extensive property per unit mass (specific volume, specific total energy)
Define continuum
The assumption of a continuous, homogeneous matter with no holes. A valid assumption if the size of the system we deal with is large relative to the space between the molecules
