1 Flashcards
Thermodynamics
Exchange and the transformations of energy in material systems
Energy (Е)
Fundamental property of objects which can be transferred and converted from one form into another but cannot be created or destroyed. Forms of energy: mechanical (kinetic and potential), thermal, chemical, electric, nuclear, radiant energy.
Thermodynamic state of systems
Relation to the environment, it can either be equillibrium or non-equillibrium state which is described by the values of thermodynamic state variables. The values of state variables are characteristic for each specific thermodynamic state:
Internal energy (U)
Free energy (F-Helmholz; G-Gibbs
Entropy (S)
Enthalpy (H)
A heat of reaction at a constant volume
Predicts whether a chemical reaction will occur spontaneously
equilibrium max = Measurement of disorder
The sum of the internal energy and the product of the pressure and volume of a thermodynamic system
isolated closed open
isolated: no exchange of material and energy between system and environment
open: enchange of energy between system and environment
open: exchange och both energy and material between system and envrironment
Thermodynamic process
Transition of thermodynamic systems from one state into another and change of the values of state variables
0th law
If two systems are in thermal equilibrium with a third, they are also in thermal equilibrium with each other temperature – measure of for the heat content of a body or system.
First law
Deals with internal energy (U), heat (Q) and work (A). Shows how internal energy of a thermodynamic system can change:
equaltion:
Second law
Defines the direction of thermodynamic processes and the state function entropy (S = ΔQ/T ). Heat cannot be spontaneously transferred from colder
to warmer body. Spontaneous processes in isolated systems always lead to increase of entropy. ΔS ≥ 0
Third law
At zero temperature (T = 0°К = -273,15оС) the entropy of a system is approaching a constant minimum value.
