- 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