| Term | Definition |
|---|
| energy | capacity to do work or produce heat |
| law of conservation of energy | energy can be converted from one form to another but can be neither created nor destroyed |
| potential energy | energy due to position or composition |
| kinetic energy | ½mv²; energy due to motion |
| frictional heating | kinetic energy transferred to outside environ. |
| temperature | prop. that reflects random motion of particles in substance |
| heat | transfer of energy between two objects due to temp. diff. |
| work | force acting over a distance |
| pathway | spec. conditions which determine the way energy transfer is divided between work & heat |
| state function (property) | property that depends only on present state |
| state function | energy (state function or not?) |
| not a state function | heat (state function or not?) |
| not a state function | work (state function or not?) |
| system | part of the universe studied |
| surroundings | everything in the universe other than sys. |
| exothermic | rxn produces heat; heat is a product |
| endothermic | rxn absords heat; heat is a reactant |
| energy gained by surr. = | energy lost by sys. |
| energy lost by sys. = | energy gained by surr. |
| ΔPE | change in potential energy; net quantity of energy transferred to surr. through heat |
| thermodynamics | study of energy & its interconversions |
| first law of thermodynamics | the energy of the universe is constant; ΔE = q - w' |
| E | internal energy of a system; sum of kin. & pot. energies of all particles of sys.; can be changed by flow of work/heat/both; ΔE (change in sys.'s internal energy) = q (heat) + w (work) |
| parts of thermodynamic quantities | number & sign which reflects sys.'s point of view |
| expansion | work done by a gas |
| compression | work done to a gas |
| H | enthalpy; H = E (internal energy) + PV |
| state function | enthalpy (state function or not?) |
| - ΔH | exothermic rxn |
| + ΔH | endothermic rxn |
| calorimeter | device used to exp. determine heat assoc. w. a chem. rxn |
| calorimetry | the science of measuring heat; based on observed temp. change when a body absorbs or discharges energy as heat |
| C | heat capacity of a substance, measuring calorimetry; = heat absorbed / increase in temp. |
| specific heat capacity | heat energy req. to raise one unit ° per one unit amt. of substance |
| molar heat capacity | heat capacity in units per mole |
| constant-pressure calorimetry | press. remains constant; q = ΔH |
| heat energy = | (mass, in g) (spec. heat capacity) (ΔT) |
| Hess's Law | "the ends justify the means;" going from partic. set of reactants to partic. set of products, change in enthalpy is the same whether the rxn takes place in one step or a series of steps |
| Hess's Law (equation) | ΔH (rxn) = ∑[ΔH(products)] - ∑[ΔH(reactants)] |
| endothermic (q or w - pos. or neg.?) | q or w is pos. b.c. sys.'s energy is increasing |
| exothermic (q or w - pos. or neg.?) | q or w is neg. b.c. sys.'s energy is decreasing |
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