Theory Kinetic

• Thermodynamics

  A branch of physics dealing with the study of the energetic effects of all physical and chemical transformations that affect changes in the internal energy of the analyzed systems
• What thermodynamics deals with

  • Energy effects of chemical reactions
  • Transformations involving ions
  • Phase transformations
  • Nuclear transformations
  • Electricity
• that affect changes in the internal
• Thermodynamic system


  A system of interacting bodies which, taken as a whole, exhibits certain properties called thermodynamic state parameters. A single molecule is not a thermodynamic system, but a sufficiently large number of them is already so

  
• Types of phases


  • Gaseous
  • Liquid
  • Solid
• Phase transformation


  The transition of any phase of the system from one state of matter to another

  
• Types of thermodynamic systems

  • Open
  • Closed
  • Isolated
• Conservation of energy - Energy is never created or destroyed – it is only transferred or transformed from one form to another
• Energy transformations


  • In a light bulb, electrical energy is transformed into heat energy and light energy
  • In a water fall, gravitational energy is transformed into kinetic energy
  • In a battery, chemical energy is transformed into electrical energy
• The higher an object is from the earth, the greater it's gravitational potential
• Energy resources are used to produce electrical energy from other forms of energy
• Kinetic-molecular theory


  Matter is composed of tiny particles that are always in motion
• Matter is any substance that occupies physical space
• Kinetic theory of matter

  Matter is made of tiny particles (i.e. atoms and molecules) and that they are always in constant motion

  
• Body temperature


  A quantity that determines the direction of energy flow when the body is in contact with another. Energy ("heat") flows from a body with a higher temperature to a body with a lower temperature

  
• Absolute zero


  A temperature equal to zero in a thermodynamic temperature scale, corresponds to −273.15 °C = 0 K. According to the third law of thermodynamics, this is the lowest possible temperature to which a given thermodynamic system can be cooled. At this temperature, the movement of matter molecules disappears, so there is no thermal energy
• Kelvin scale


  Zero on the Kelvin scale (absolute scale) means the lowest theoretically possible temperature that a body can have. This is the temperature at which (according to classical physics) all vibrations of molecules cease (absolute zero). However, this temperature cannot be achieved – it was calculated on the basis of a function that makes the temperature dependent on the kinetic energy in perfect gases. This function was developed by William Thomson, Lord Kelvin, in whose honor the scale and unit of temperature were named
• State parameters of a thermodynamic system

  • Pressure (p)
  • Temperature (T)
  • Volume (V)
  • Number of moles of components (n)
  • Concentrations (C) of the components in each phase
• Heat


  Thermal energy transferred from a hotter system to a cooler system that are in contact

  
• Temperature


  A measure of the average kinetic energy of the atoms or molecules in the system
• When the two systems in contact are at the same temperature, we say they are in thermal equilibrium
• Total energy of a system (Ec)

  The sum of kinetic energy (Ek), potential energy (Ep), and internal energy (U)
• First law of thermodynamics

  Specifies the energy balance found in any thermodynamic system
• Heat


  A form of change in the energy of a system depending on the process path. The flow of energy as a result of the disordered motion of molecules is heat (thermal flow of energy)

  
• Anabolism


  A group of chemical reactions, as a result of which complex compounds are formed from simple substrates, accumulating energy. This is the part of metabolism that is associated with the growth of body tissues
• Catabolism


  All metabolic chemical reactions leading to the breakdown of complex chemical compounds into simpler molecules, the opposite of anabolism. Exo-energy reaction, releasing energy
• Organism as a thermodynamic system

  An open system in which irreversible processes take place striving for a state of equilibrium. Conditions: constant temperature (isothermal), constant pressure (isobaric). Irreversible processes lead the system from a more to a less organized state - until the flows cease (reaching an equilibrium state = death of the biological system)
• Entropy (S)


  A thermodynamic function of state, determining the direction of spontaneous processes in an isolated thermodynamic system. A quantitative thermodynamic measure of the disorder of matter and energy of a system
• According to the second law of thermodynamics, heat transfer always occurs from a body with a higher temperature to a body with a lower temperature

  
• Third law of thermodynamics

  The entropy of a thermodynamic system tends to zero, when the absolute value of the temperature of that system tends to zero. This principle also results in the inability to reach the absolute zero temperature, as well as the behavior of thermodynamic quantities near this temperature
• Heat transport mechanisms


  • Conduction - Thermal conductivity
  • Convection - Heat transfer (lifting)
  • Radiation

  
• Second law of thermodynamics

  Determines the direction of thermodynamic processes and the equilibrium state of the physical system
• Third law of thermodynamics


  Imposes limits on temperature and entropy
• Fourth law of thermodynamics

  Principle of minimum entropy production - the passage of systems around the equilibrium state through non-equilibrium states in which the production of entropy is the smallest
• Conduction


  The process of heat transfer by conduction between bodies of different temperatures in direct contact with each other. It consists in the transfer of kinetic energy of the disorderly movement of molecules as a result of their collisions, leading to temperature equalization.

  
• Convection


  The exchange of heat through the macroscopic movement of a fluid. It can be divided into forced convection (driven by fans, pumps, etc.) and free/natural convection (driven by buoyancy forces).

  
• Thermal radiation


  Electromagnetic radiation emitted by all bodies, mainly from the infrared range, caused by thermal movements inside bodies. The amount of radiation depends on body temperature.
• Different electromagnetic wavelengths are assigned different names (from the longest to the shortest wavelength): radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, gamma radiation.
• Stefan-Boltzmann law


  A law describing the total power radiated by a perfectly black body at a given temperature.
• Kirchhoff's law


  The ratio of the emission capacity of a body to its absorption capacity at the same temperature is constant and equal to the emission capacity of a black body.