Flashcards in Energy Deck (21):
What is Internal Energy (U)?
The total energy in a system - both kinetic and potential
What are the three types of kinetic energy?
What is Thermal Energy
The three types of kinetic energy (translation, rotation, vibration)
What are the two types of Potential Energy?
כוחות תוך מולקולריים
כוחות בין מולקולרים
What is thermochemistry?
The study of energy changes that occur during chemical reactions
What are the three types of systems in thermochemistry?
How can energy be transferred between the system and its surroundings?
Heat (the reaction in the system changes the temp of its surroundings)
Work (the reaction forces work to be done, i.e, moves matter through distance)
What is "negative energy" or "positive energy"?
NOTHING! Those are the wrong terms to use!
The sign of work or heat signifies the direction of energy flow
What happens when Thermal Equilibrium is reached?
Heat stops "flowing" from a high temp to a lower temp
What is a closed system?
A system that allows energy to flow in and out, but not matter
What is an isolated system?
A system that doesn't allow energy or matter to flow in and out
Will an ice cube melt faster if placed on wood or metal? Why?
Metal. Not only with the molecules that make contact with the ice directly, transfer their heat, but also molecules that hit other places of the metal with transfer the heat through the metal.
What is compression?
Work done ON the system. The system GAINS energy (+w)
What is expansion?
Work done BY the system. The system LOSES energy (-w)
w = -P Δ V
Work = - pressure * change in volume
The minus sign signals that the system lost energy
What is a state function?
A function whose value depends only on the present state of the system and does not depend on how that state was reached
Is a function that describes climbing a mountain a state function?
Yes. The function is based only on the end state and the beginning state (and not the path that you took up the mountain).
Is energy a state function?
What is the Law of Conservation of Energy?
חוק שימור האנרגיה
Energy can be exchanged between a system and its surroundings, but no energy can be created or destroyed.
What is the equation for the internal energy change in a system?
The difference between its final and initial states:
∆U=U final-U initial