Thermodynamics/Thermochemistry & Work/Energy Flashcards
What is a system?
the matter being observed, the total amount of reactants and products in a chemical reaction
What is an isolated system?
A system that cannot exchange energy (heat and work) or matter with the surroundings?
Energy can be transferred in the forms of
- Work: mechanical
- Electrically
- Heat: thermodynamics
- Radiation
What is a closed system?
A system that can exchange energy (heat and work) but not matter with the environment
What is an open system?
A system that can exchange both energy (heat and work) with the surroundings
ex: a boiling pot of water
What is the equation for the first law of thermodynamics?
Delta U=Q-W
Describe an isothermal process
The temperature is constant–so there is no heat added t making Q, Q=W so the heat added to a system is equal to the work done by the system–so U is Zero
Delta U=0
What is a process?
When a system undergoes a change in one or more of its properties
____ processes occur when no heat is exchanged between the system and the environment
Adiabatic
Describe the properties of an Adibatic process
-no heat is exchanged so Q=0
so Delta U will equal -W so the change in internal energy is equal to the work done ON the system since W is negative
A ____ process occurs when the pressure of the system is constant
Isobaric
How does the graph of an isobaric process appear?
Straight line, with a slope of zero
A ____ process experiences no change in volume
Isovolumetric (Isochoric) System
Delta U = Q in what type of system and why?
Isovolumetric.
If the volume is constant (no compression or expansion), no work is being done so W=0 leaving Delta U=Q
How does an isovolumetric graph appear?
Vertical Line
___ is the transfer of energy from one substance to another as a result in differences in temperature
Heat
_____ is the average kinetic energy of the particles of a substance
Temperature
_____ states that objects are in thermal equilibrium when their temperatures are equal
Zeroth law of thermodynamics
What does the first law of thermodynamics state?
The change in total internal energy of a system is equal to the difference in amount of energy transferred into the system and the amount of energy transferred out of the system
Heat is a _____ function not a _____ function
Process, state
What are the most important process functions
Work (W) and Heat (Q)
What is a process function?
The way by which an equilibrium state is reached
The processes in which heat is absorbed (Q>0) is
endothermic
The process in which heat is released (Q<0) is
exothermic
