Midterm 1 Flashcards
Activated complex
Aka. Transition state
Unstable combination of reactant species forming during a chemical reaction
Activation energy
Minimum energy necessary in order for a reaction to take place
Arrhenius equation
Relationship between reaction rate’s constant, activation energy, and temperature
Average rate
The instantaneous rate of change over time
Change in concentration / change in time
Bimolecular equation
Elementary reaction involving two reactant entities
Catalyst
Substance that increases the rate of a reaction without itself being consumed by the reaction
Collision theory
Model that emphasizes the energy and orientation of molecular collisions to explain and predict reaction kinetics
Elementary reaction
Reaction that takes place in a single step, precisely as depicted in its chemical equation
Frequency factor (A)
Proportionally constant in the Arrhenius equation, relatives to the relative number of collisions having an orientation capable of leading to product formation
Half-life of a reaction (t1/2)
Time required for half a given reaction to be consumed
Heterogeneous catalyst
Catalyst present in a different phase from the reactant, furnishings surface at which a reaction can occur
Homogenous catalyst
Catalyst present in the same phase as the reactant
Initial rate
Instantaneous rate at t=0s
Instantaneous rate
Rate of a chemical reaction at any instant in time, determine by the slopes of the line tangential to a graph of concentration as a function of time
Integrated rate law
Equation that relates the concentration of a reactant to elapsed time of reaction
Intermediate
Entities produced in one step of a reaction mechanism and consumed in a subsequent step
Molecularity
Number of reactant entities involved in an elementary reaction n
Overall reaction order
Sum of the reaction orders for each substance represented in the rate law
Rate constant (k)
Proportionality constant in a rate law
Rate expression
Defining reaction rate as change in amount, concentration, or pressure of reactant or products species per unit time
Rate law
Showing the dependence of reaction rate on the rate constant and the concentration of one or more reactants
Rate of reaction
Measure of the speed at which a chemical reaction takes place
Rate-determining step
- Slowest elementary reaction in a reaction mechanism
- determines rate of the overall reaction
Reaction diagram
Used in chemical kinetics to illustrate various properties of a reaction
Reaction mechanism
Stepwise sequence of elementary reactions by which a chemical change takes place
Reaction order
Value of an exponent in a rate law
Termolecular reaction
Elementary reaction involving three reactant entities
Unimolecular reaction
Elementary reaction involving a single reactant entity
Half-life for a zero-order reaction
T1/2 = [A]0/2k
Integrated rate law for zero-order reactions
Ln [A]t = -kt + ln [A]0
