# Thermo, set 1

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1. system
a quantity of matter or a region in space chosen for study
2. surroundings
physical space outside the system boundary
3. boundary
real or imaginary surface that separates the system from its surroundings. It may be fixed or movable.
4. closed system
exchange of energy but NOT matter
5. open system
(control volume), exchange of energy and matter
6. control surface
boundary of an open system
7. isolated system
can exchange NEITHER energy nor matter
8. property
a characteristic of a system in equilibrium. It is independent of the path used to arrive at the system condition.
9. Intensive property
independent of amount of material (i.e.temperature, pressure, age, color, etc.)

Ratio of two extensive = intensive
10. extensive property
Dependent of amount of material (mass, volume, total energy, etc.)
11. weight
a force. W = mg
12. equilibrium
a system that maintains thermal (uniform temperature), mechanical (uniform pressure), phase (mass of two phases), and chemical equilibrium. Microscopic processes still occur and rate of process is balances by reverse process.
13. Process
Any change from one state to another
operating for long periods of time under the same conditions
15. state postulate
a thermodynamic state of a simple compressible sysem is completely specified by two independent, intensive properties
16. cycle
a process with identical end states
17. Pressure
Force/Area.
18. absolute pressure
• measured relative to absolute zero (absolute vacuum)
• P abs = P atm +/- P gage
19. atmospheric pressure
aka gage or vacuum pressure
20. Temperature
energy content of a mass
21. heat
• (Q) transfer; the difference in temperature that causes energy to flow between bodies
• Also difference in enthalpy!
22. zeroth law of thermo
if two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other
23. Phase
physically homogeneous/mechanically separable part of system (i.e. vapor, liquid, mineral)
24. component
Expresses compositional variations in system. H20 is one-component system, only if phases are interest
25. Energy states
• Unstable: falling/rolling
• Stable: at rest in LOWEST energy state
• Metastable: in low-energy perch
• equilibrium is NOT steady state
26. thermal equilibrium
No net transfer of energy as heat between two regions contacted by diathermic wall (same temp). Different temp, heat would flow from hot to cold region.
27. Mechanical Equilibrium
Two regions separated by a wall have equal pressure. But if one region had high pressure, it would move the wall toward the region with low pressure.
28. reversible
Idealized process, proceeds through sequence of equilibrium states. No finite deviation from equilibrium.
29. spontaneous
real/natural process where internal state of system changes to approach equilibrium from initial non-equilibrium state
30. Endothermic
absorbs heat (+Q, or delta H > 0 )
31. Exothermic
releases heat (-Q, or delta H < 0)
 Author: KatieMac ID: 4937 Card Set: Thermo, set 1 Updated: 2010-03-13T14:56:05Z Folders: Description: Chemical Thermodynamics Show Answers: