Module 1 - Energy, Entropy, And Spontaneuous Change Flashcards
Physical change (def)
No change in chemical composition of the system
Ex. Heating, cooling, expansion, compression, phase change
Chemical change (def)
Chemical composition of system is changed by chemical reaction
Kinetic energy (def)
Energy an object or a system has by virtue of its motion
Ek = 1/2 mv^2
Potential energy (def)
Energy an object of a system has by virtue of its position or configuration
Ex. Eg = mgh
Internal energy, U (def)
Energy an object or a system has by virtue of its molecular nature
Sum of kinetic and potential energies of all the particles in the system
Entropy (def)
A measure of the number of different ways a given amount of energy can be distributed among the molecules of the system
The key to understanding the direction of spontaneous change
System (def)
A region of the universe that we have specific interest in
Ex. Engine, electrochemical or biological cell, chemical reaction vessel
Surroundings (def)
A region outside of the system that serves as a place to make measurements of the system
Open system (def)
Both matter and energy can be exchanged with the surroundings
Ex. Open water bottle
Closed system (def)
Only energy (not matter) can be exchanged with the surroundings Ex. Closed water bottle
Isolated system (def)
Neither energy nor matter can be exchanged with the surroundings
Ex. Thermos
Heat, Q (def)
Energy that flows from a region of high temperature to a region of low temperature
Q>0 endothermic
Q<0 exothermic
Diathermic (def)
A boundary that permits heat to be transferred between the system and its surroundings
Ex. A pot used for cooking
Adiabatic (def)
A boundary that does not permit heat to be transferred between the system and its surroundings
Q = 0
Ex. A thermos
Heat capacity (def)
Amount of heat required to raise the temperature by 1 degree
Work (def)
Force•displacement
Displacement is associated with a change in the relative positions or configurations of the particles of the system
W>0 work is done on system
W<0 work is done on surroundings
Expansion work (def)
An expanding gas that pushes a piston to lift a mass against gravity
Electrical work (def)
Moving a charged particle from a region of high electrical potential to low electrical potential
Surface tension work (def)
Surface area of a liquid changes
The first law of thermodynamics
ΔU = q + w
For closed systems
OR
when a reaction occurs at a constant volume, qv = ΔU
OR
When a reaction occurs at constant pressure, qp=ΔH
Enthalpy change, ΔH
Represents the heat transferred in a constant pressure process
H = U+PV
Microstate (def)
A specific microscopic configuration describing how the molecules of a system are distributed among the available energy levels
Number of microstates in a system increases with:
Number of molecules Space available to the molecules Structural complexity of the molecules Total energy available to the molecules (total internal energy) Temperature
The second law of thermodynamics
ΔSuniv = ΔS + ΔSsurr > 0
