Term | Definition |
energy | the ability to do work or produce heat |
potential energy | energy due to position or composition |
kinetic energy | energy due to the motion of the object |
law of conservation of energy | energy can be converted from one form to another but can be neither created nor destroyed |
frictional heating | energy transferred to a surface as heat |
state function | a property of a system that does not depend on the pathway |
temperature | a measure of the random motions (average kinetic energy) of the components of a substance |
heat | flow of energy due to temperature difference |
thermal energy | the random motions of the components of an object |
heat energy | the way in which thermal energy is transferred from a hotter object to a colder object |
thermodynamics | study of energy |
first law of thermodynamics | the energy of the universe is constant (aka the law of conservation of energy) |
internal energy (E) | the sum of the kinetic and potential energies of all the "particles" in the system |
system | the part of the universe on which we wish to focus attention |
surroundings | includes everything else in the universe |
exothermic | refers to a process in which energy (as heat) flows out of the system and into the surroundings (i.e. heat released) |
endothermic | refers to a process in which energy (as heat) flows out of the surroundings into the system (heat is absorbed) |
calorimetry | the study of heat transferred in a chemical reaction |
calorimeter | an insulated apparatus containing a liquid reservoir in which the ration occurs |
calorie | the amount of energy (heat) needed to raise the temperature of one gram of water by one degree celsius |
Joule | 1 calorie = 4.184 joules |
heat capacity (C) | the amount of heat needed to increase the temperature of a substance 1 degree celsius |
specific heat capacity | the amount of energy required to change the temperature of one gram of a substance by 1 degree celsius |
thermochemistry | the study of energy changes that occur during chemical reactions and changes in state |
enthalpy (H) | the energy (heat) flow of a system at constant pressure |
thermochemical equation | a chemical equation that includes the enthalpy change |
heat of reaction | enthalpy change/heat released or absorbed in a chemical reaction (depends on the stoichiometry of the reaction), reported as *triangle* H |
heat of combustion | heat of reaction for the complete burning of one mole of a substance |
molar heat of fusion | heat absorbed by 1 mol of a substance in freezing at a constant temperature |
molar heat of solidification | the heat released by 1 mol of a substance in freezing at a constant temperature |
molar heat of vaporization | the amount of heat required to vaporize one mole of a given liquid at a constant temperature |
molar heat of condensation | the amount of heat released when one mole of a vapor condenses at its normal boiling point |
molar heat of solution | the enthalpy change caused by the dissolution of one mole of substance |
hess's law | the change in enthalpy going from a given set of reactants to a given set of products does not depend on the number of steps in the reaction |
hess's law of heat summation | if you add two or more thermochemical equations to give a final equation, then you can also add the heats of reaction to give the final heat of reaction |
standard heat of formation | the change in enthalpy that accompanies the formation of one mole of a compound from its elements with all substances in their standard states |
entropy | a measure of disorder or randomness |
second law of thermodynamics | the entropy of the universe is always increasing |