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6.5: Key Terms

Last updated

Feb 27, 2024
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- 6.4: Enthalpy
- 6.6: Key Equations

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Example and Directions
Words (or words that have the same definition)	The definition is case sensitive	(Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages]	(Optional) Caption for Image	(Optional) External or Internal Link	(Optional) Source for Definition
(Eg. "Genetic, Hereditary, DNA ...")	(Eg. "Relating to genes or heredity")		The infamous double helix	https://bio.libretexts.org/	CC-BY-SA; Delmar Larsen

Glossary Entries
Word(s)	Definition	Image	Caption	Link	Source
bomb calorimeter	device designed to measure the energy change for processes occurring under conditions of constant volume; commonly used for reactions involving solid and gaseous reactants or products
calorie (cal)	unit of heat or other energy; the amount of energy required to raise 1 gram of water by 1 degree Celsius; 1 cal is defined as 4.184 J
calorimeter	device used to measure the amount of heat absorbed or released in a chemical or physical process
calorimetry	process of measuring the amount of heat involved in a chemical or physical process
chemical thermodynamics	area of science that deals with the relationships between heat, work, and all forms of energy associated with chemical and physical processes
endothermic process	chemical reaction or physical change that absorbs heat
energy	capacity to supply heat or do work
enthalpy (H)	sum of a system’s internal energy and the mathematical product of its pressure and volume
enthalpy change (ΔH)	heat released or absorbed by a system under constant pressure during a chemical or physical process
exothermic process	chemical reaction or physical change that releases heat
expansion work (pressure-volume work)	work done as a system expands or contracts against external pressure
first law of thermodynamics	internal energy of a system changes due to heat flow in or out of the system or work done on or by the system
heat (q)	transfer of thermal energy between two bodies
heat capacity (C)	extensive property of a body of matter that represents the quantity of heat required to increase its temperature by 1 degree Celsius (or 1 kelvin)
Hess’s law	if a process can be represented as the sum of several steps, the enthalpy change of the process equals the sum of the enthalpy changes of the steps
hydrocarbon	compound composed only of hydrogen and carbon; the major component of fossil fuels
internal energy (U)	total of all possible kinds of energy present in a substance or substances
joule (J)	SI unit of energy; 1 joule is the kinetic energy of an object with a mass of 2 kilograms moving with a velocity of 1 meter per second, 1 J = 1 kg m²/s and 4.184 J = 1 cal
kinetic energy	energy of a moving body, in joules, equal to (where m = mass and v = velocity)
nutritional calorie (Calorie)	unit used for quantifying energy provided by digestion of foods, defined as 1000 cal or 1 kcal
potential energy	energy of a particle or system of particles derived from relative position, composition, or condition
specific heat capacity (c)	intensive property of a substance that represents the quantity of heat required to raise the temperature of 1 gram of the substance by 1 degree Celsius (or 1 kelvin)
standard enthalpy of combustion	heat released when one mole of a compound undergoes complete combustion under standard conditions
standard enthalpy of formation	enthalpy change of a chemical reaction in which 1 mole of a pure substance is formed from its elements in their most stable states under standard state conditions
standard state	set of physical conditions as accepted as common reference conditions for reporting thermodynamic properties; 1 bar of pressure, and solutions at 1 molar concentrations, usually at a temperature of 298.15 K
state function	property depending only on the state of a system, and not the path taken to reach that state
surroundings	all matter other than the system being studied
system	portion of matter undergoing a chemical or physical change being studied
temperature	intensive property of matter that is a quantitative measure of “hotness” and “coldness”
thermal energy	kinetic energy associated with the random motion of atoms and molecules
thermochemistry	study of measuring the amount of heat absorbed or released during a chemical reaction or a physical change
work (w)	energy transfer due to changes in external, macroscopic variables such as pressure and volume; or causing matter to move against an opposing force

bomb calorimeter | device designed to measure the energy change for processes occurring under conditions of constant volume; commonly used for reactions involving solid and gaseous reactants or products

calorie (cal) | unit of heat or other energy; the amount of energy required to raise 1 gram of water by 1 degree Celsius; 1 cal is defined as 4.184 J

calorimeter | device used to measure the amount of heat absorbed or released in a chemical or physical process

calorimetry | process of measuring the amount of heat involved in a chemical or physical process

chemical thermodynamics | area of science that deals with the relationships between heat, work, and all forms of energy associated with chemical and physical processes

endothermic process | chemical reaction or physical change that absorbs heat

energy | capacity to supply heat or do work

enthalpy (H) | sum of a system’s internal energy and the mathematical product of its pressure and volume

enthalpy change (ΔH) | heat released or absorbed by a system under constant pressure during a chemical or physical process

exothermic process | chemical reaction or physical change that releases heat

expansion work (pressure-volume work) | work done as a system expands or contracts against external pressure

first law of thermodynamics | internal energy of a system changes due to heat flow in or out of the system or work done on or by the system

heat (q) | transfer of thermal energy between two bodies

heat capacity (C) | extensive property of a body of matter that represents the quantity of heat required to increase its temperature by 1 degree Celsius (or 1 kelvin)

Hess’s law | if a process can be represented as the sum of several steps, the enthalpy change of the process equals the sum of the enthalpy changes of the steps

hydrocarbon | compound composed only of hydrogen and carbon; the major component of fossil fuels

internal energy (U) | total of all possible kinds of energy present in a substance or substances

joule (J) | SI unit of energy; 1 joule is the kinetic energy of an object with a mass of 2 kilograms moving with a velocity of 1 meter per second, 1 J = 1 kg m²/s and 4.184 J = 1 cal

kinetic energy | energy of a moving body, in joules, equal to (where m = mass and v = velocity)

nutritional calorie (Calorie) | unit used for quantifying energy provided by digestion of foods, defined as 1000 cal or 1 kcal

potential energy | energy of a particle or system of particles derived from relative position, composition, or condition

specific heat capacity (c) | intensive property of a substance that represents the quantity of heat required to raise the temperature of 1 gram of the substance by 1 degree Celsius (or 1 kelvin)

standard enthalpy of combustion | heat released when one mole of a compound undergoes complete combustion under standard conditions

standard enthalpy of formation | enthalpy change of a chemical reaction in which 1 mole of a pure substance is formed from its elements in their most stable states under standard state conditions

standard state | set of physical conditions as accepted as common reference conditions for reporting thermodynamic properties; 1 bar of pressure, and solutions at 1 molar concentrations, usually at a temperature of 298.15 K

state function | property depending only on the state of a system, and not the path taken to reach that state

surroundings | all matter other than the system being studied

system | portion of matter undergoing a chemical or physical change being studied

temperature | intensive property of matter that is a quantitative measure of “hotness” and “coldness”

thermal energy | kinetic energy associated with the random motion of atoms and molecules

thermochemistry | study of measuring the amount of heat absorbed or released during a chemical reaction or a physical change

work (w) | energy transfer due to changes in external, macroscopic variables such as pressure and volume; or causing matter to move against an opposing force

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