1 / 11

The Laws of Thermodynamics

The Laws of Thermodynamics. Metro Community College 7/14/2010. Main Definitions. Thermodynamics – The study of processes in which heat is transferred as heat and as work.

marilu
Télécharger la présentation

The Laws of Thermodynamics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Laws of Thermodynamics Metro Community College 7/14/2010

  2. Main Definitions • Thermodynamics – The study of processes in which heat is transferred as heat and as work. • Heat is the transfer of energy due to a difference in temperature. (Kinetic energy due to molecular motion moves from high temperature and internal energy to low.) • Work is a transfer of energy due to other means, not a temperature difference.

  3. Other definitions • System – the set of objects or object we wish to consider. • Environment – Everything that surround the system we are studying. • Open system – a system where mass and energy can be exchanged with the environment • Closed system – a system where no mass leaves the system, but energy can. • Isolated system – a system where no energy in any form (or mass) leaves or enters the system

  4. The First Law of Thermodynamics The First Law of Thermodynamics – The change in internal energy of a closed systemequals the heat added to the system minus the work done by the system. (A statement of the conservation of energy.)

  5. Possible Processes • Isothermal process – a process where the temperature does not change. PV=constant. • Isobaric process – a process where the pressure does not change. T/V = constant. • Isochoric process – a process where volume does not change. T/P = constant. This is also called an isometric process. • Adiabatic process – process where no heat is added or removed. Q = 0.

  6. Isothermal Process • Temperature cannot change in an isothermal process so internal energy cannot change. Internal energy (U) is proportional to temperature. • Heat added to the system equals the work done by the system.

  7. Isobaric Process • Pressure does not change. Therefore the work done by the system results in a change in volume (increase). Work on the system results in a decrease in volume. • Temperature and volume must be adjusted to keep pressure constant.

  8. Isochoric Process • The volume does not change so no work is done in an isochoric process.

  9. Adiabatic Process • No heat is added to the system. Q = 0. • This occurs where the work done on or by the system happens so quickly that heat does not have time to move.

  10. Second Law of Thermodynamics • Heat flows naturally from a hot to a cold object; heat will not flow spontaneously from a cold to a hot object. (Clausius) • The total entropy of any system plus that of its environment increases as a result of a natural process. • Natural processes tend to move toward a state of greater disorder

  11. Summary • Zeroth Law-If a System is in equilibrium with two other systems that the two other systems are also in equilibrium. • First Law – Energy is conserved • Second Law – Disorder increases in natural processes.

More Related