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Ch 17 Vocabulary
Term | Definition |
---|---|
Thermochemistry | The study of changes in heat energy that accompany chemical rxns and physical changes |
Calorimeter | The heat absorbed or released in a chemical or physical change is measured with this |
Temperature | A measure of the average kinetic energy of the particles |
Joule | the SI unit of heat energy as well as all other forms of energy |
Heat/Heat energy | Can be thought of as the sum total of the kinetic energies of the particles in a sample of matter |
Specific Heat | The amount of heat nrg required to raise the temp of one gram of substance by 1C or 1K |
Heat of Reaction | The quantity of heat released or absorbed during a chemical reaction |
Thermochemical Equation | An equation that includes the quantity of heat released or absorbed during the rxn as written |
Enthalpy | The heat content of a system at constant pressure (Delta H) |
Enthalpy Change | The amount of heat absorbed or lost by a system during a process at constant pressure |
Molar Heat of Formation | The heat released or absorbed when 1 mole of a compound is formed by combination of elements |
Heat of Combustion | One mole of reactant, whereas the heat of formation is defined in terms of 1 mole of product |
Hess's Law | The overall enthalpy change in a rxn is equal to the sum of enthalpy changes for the individual steps in the process |
Entropy | A measure of the degree of randomness of the particles, such as molecules, in a system (Delta S) |
Free Energy | The combined enthalpy-entropy function (G) |
Free-energy Change | The difference between the change in enthalpy and the product of the K temp and entropy change |
Reaction Mechanism | The step-by-step sequence of reactions by which the overall chemical change occurs |
Intermediates | Species that appear in some steps but not in the net equation |
Homogeneous Reactions | A reaction whose reactants and products exist is a single phase |
Collision Theory | The set of assumptions regarding collisions and reactions |
Activation Energy | The minimum energy required to transform the reactants into an activated complex |
Activated Complex | A transitional structure that results from an effective collision and that persists while bonds are breaking and new bonds are forming |
Reaction Rate | The change in concentration of reactants per unit time as a reaction proceeds |
Chemical Kinetics | The area of chemistry that is concerned with reaction rates and reaction mechanisms |
Heterogeneous Reactions | Involve reactants in two different phases |
Catalyst | A substance that changes the rate of a chemical rxn without itself being permanently consumed |
Catalysis | The action of a catalyst |
Homogenous Catalyst | A catalyst that is in the same phase as all the reactants and products in a rxn |
Heterogeneous Catalyst | When the phase is different from that of the reactants |
Rate Law | An equation that relates reaction rate and concentrations of reactions |
Rate-determining Step | The slowest rate step |