Exam 4 Definitions

Energy

the ability to do work

work

energy used to cause a massed object to move

heat

energy used to cause the temperature of an object to rise

Thermodynamics

the study of energy transformations

thermochemistry

Study of energy changes in chemical reactions.

kinetic energy

energy of motion

potential energy

stored energy

joule (J)

SI unit of energy

System

the molecules under study

surroundings

everything outside the system

first law of thermodynamics

Energy cannot be created or destroyed

internal energy

the sum of all kinetic and potential energies of all components of a system

Endergonic

absorbed energy from surroundings

exergonic

released energy to the surroundings

q

heat

w

work

enthalpy

heat absorbed or released in a reaction

entropy

a measure of the disorder of a system

spontaneous process

proceed without any outside assistance

second law of thermodynamics

when energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes

nonspontaneous process

Requires energy input to occur.

reversible process

the system changes so that the system and surroundings can be returned to the original state by exactly reversing the process

Irreversible Process

not able to be restored to initial state

microstate

a single possible arrangement of position and kinetic energy of molecules

Translational Motion

movement of the entire molecule from one place to another

Vibrational Motion

periodic motion of atoms within a molecule

rotational motion

rotation of the molecule about an axis

Third Law of Thermodynamics

the entropy of a pure crystalline substance at absolute zero is zero