Physics and Math Chapter 3: Thermodynamics Flashcards
What is the zeroth law of thermodynamics?
states that objects are in thermal equilibrium when they are at the same temperature
What is temperature?
a qualitative measure of how hot or cold and object is; quantitatively, it is related to the average kinetic energy of the particles that make up a substance.
What is thermal expansion?
Describes how a substance changes in length or volume as a function of the change in temperature.
What is the thermodynamic system versus surroundings?
System = portion that we are interested in Surroundings = everything that is not a part of the system
Isolated systems
do not exchange matter or energy with the surroundings
Closed systems
Exchange energy, but not matter with their surroundings
Open systems
Exchange both energy and matter with their surroundings
What are state functions?
pathway independent and are not defined by a process. Ex. pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy and entropy are all state functions.
What are process functions?
describe pathway from one equilibrium state to another. Work and heat are process functions.
What is the first law of thermodynamics?
statement of conservation of energy. The total energy in the universe can never decrease or increase
What is the total internal energy in a closed system?
Heat flow into the system minus the work done by the system.
What is heat?
The process of energy transfer between two objects at different temperatures that occurs until the two objects come into thermal equilibrium (reach the same temperature)
What is specific heat?
The amount of energy necessary to raise one gram of a substance by one degree Celsius or one unit Kelvin
What is the specific heat of water?
1 cal/g*K
What is the heat of transformation?
During a phase change, heat energy causes changes in the particles’ potential energy and energy distribution, but not kinetic energy. Therefore, there is no change in temperature.
Isothermal process.
temperature is constant, so change in internal energy is 0
Adiabatic process
no heat is exchanged
isobaric process
pressure is constant
Isovolumetric process (isochoric)
volume is held constant and work by or on the system is 0
What is the second law of thermodynamics?
in a closed system, energy will spontaneously and irreversibly go from being localized to being spread out.
Entropy
a measure of how much energy has spread out or how spread out energy has become
What are microstates?
As microstates increase, the potential energy of a molecule is distributed over that larger number of microstates, increasing entropy
Are natural processes reversible?
Yes, every natural process is ultimately reversible.
When is delta U positive/negative?
(+) Increasing temperature
(-) decreasing temperature
When is heat (Q) positive/negative?
(+) heat flows into the system
(-) Heat flows out of the system
When is work (W) positive/negative?
(+) work is done by the system (expansion)
-) work is done on the system (compression
