AP Chemistry Chapter 6: Thermodynamics

energy

the ability to do work

law of conservation of energy

the law that states that energy cannot be created or destroyed but can be changed from one form to another

potential energy

stored energy that results from the position or shape of an object

kinetic energy

the energy an object has due to its motion

heat

The energy transferred between objects that are at different temperatures

work

force x distance

pathway

The specific conditions that control how energy transfer is divided between work and heat

state function (property)

a property that is independent of the pathway

system

the chemical or physical change that you are studying

surroundings

everything outside the system

exothermic

Chemical Reaction in which energy is primarily given off in the form of heat

endothermic

(of a chemical reaction or compound) occurring or formed with absorption of heat

thermodynamics

The study of energy transformations that occur in a collection of matter.

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

internal energy

the sum of the kinetic and potential energies of all particles in the system

enthalpy

The heat content of a system at constant pressure

calorimeter

an insulated device used to measure the absorption or release of heat in chemical or physical processes

calorimetry

The precise measurement of heat flow out of a system for chemical and physical processes

heat capacity

the number of heat units needed to raise the temperature of a body by one degree.

specific heat capacity

the energy required to raise the temperature of one gram of a substance by one degree Celsius

molar heat capacity

the energy required to raise the temperature of one mole of a substance by one degree Celsius

constant-pressure calorimetry

the measurement of heat using a simple calorimeter to determine the changes in enthalpy (heats of reaction) for reactions occurring in solution; the pressure (atmospheric pressure) remains constant during the process

constant-volume calorimetry

the measurement of heat at a constant volume to find the change in internal energy of the system; requires the use of a "bomb" calorimeter

Hess's Law

the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process

standard enthalpy of formation

enthalpy change if 1 mole of compound in standard state were formed directly from its elements

standard state

a reference state for a specific substance defined according to a set of conventional definitions

fossil fuels

Coal, oil, natural gas, and other fuels that are ancient remains of plants and animals.

petroleum

liquid fossil fuel; oil

natural gas

flammable gas, consisting largely of methane and other hydrocarbons, occurring naturally underground (often in association with petroleum) and used as fuel.

coal

A fossil fuel that forms underground from partially decomposed plant material

greenhouse effect

Natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases

syngas

synthetic gas, a mixture of carbon monoxide and hydrogen, obtained by coal gasification