1st Law of Thermodynamics Flashcards
What is the first law of thermodynamics?
energy can neither be created or destroyed; it can only change forms
What is a system?
a quantity or region of interest
What is a state?
a property whose value doesn’t depend on the path taken
What is a process?
a change of state from one state point to another
What are properties independent of?
process path
What kind of properties are work and heat?
directional properties
What is the sign convention for work done on a system?
positive
What is the sign convention for heat transfer from surroundings?
negative
What is true for a closed system?
*no fluid/ mass can cross the system boundary
*energy can cross boundary as work or heat
*volume is not necessarily fixed
What are the 3 main components of energy?
- internal energy
- kinetic energy
- potential energy
these make up the total internal energy
What is the equation that describes the first law of thermodynamics?
Q - W = delta E
What is true for isolated systems?
*adiabatic process
*no heat transfer, Q= 0
*W net = Win - Wout
What is the internal energy?
the molecular energy of a system and may exist in sensible, latent, chemical and nuclear forms
What is the specific heat capacity?
the energy required to raise the temperature of a unit mass of a substance by 1 degree
