Kinetics

Question 1

Rate of Reaction

Answer 1

Measure of the speed at which a chemical reaction takes place

Question 2

Rate Expression

Answer 2

Mathematical representation defining reaction rate as change in amount, concentration, or pressure of reactant or product species per unit time

Question 3

Average Rate

Answer 3

Rate of a chemical reaction computed as the ratio of a measured change in amount or concentration of substance to the time interval over which the change occurred

Question 4

Instantaneous Rate

Answer 4

Rate of a chemical reaction at any instant in time, determined by the slope of the line tangential to a graph of concentration as a function of time

Question 5

Initial Rate

Answer 5

Instantaneous rate of a chemical reaction at t=0s (immediately after the reaction has begun)

Question 6

Catalysts

Answer 6

Substance that increases the rate of a reaction without itself being consumed by the reaction

Question 7

Rate Laws (Rate Equation or Differential Rate Laws)

Answer 7

Mathematical equation showing the dependence of reaction rate on the rate constant and the concentration of one or more reactants

Question 8

Rate Constant (k)

Answer 8

Proportionality constant in a rate law

Question 9

Reaction Orders

Answer 9

Value of an exponent in a rate law (for example, zero order for 0, first order for 1, second order for 2, and so on)

Question 10

Overall Reaction Order

Answer 10

Sum of the reaction orders for each substance represented in the rate law

Question 11

Method of Initial Rates

Answer 11

Common experimental approach to determining rate laws that involves measuring reaction rates at varying initial reactant concentrations

Question 12

Integrated Rate Laws

Answer 12

Equation that relates the concentration of a reactant to elapsed time of reaction

Question 13

Half-Life of a Reaction (t1/2)

Answer 13

Time required for half of a given amount of reactant to be consumed

Question 14

Collision Theory

Answer 14

Model that emphasizes the energy and orientation of molecular collisions to explain and predict reaction kinetics

Question 15

Activated Complex (Transition State)

Answer 15

Unstable combination of reactant species formed during a chemical reaction

Question 16

Activation Energy (Ea)

Answer 16

Minimum energy necessary in order for a reaction to take place

Question 17

Reaction Diagram

Answer 17

Used in chemical kinetics to illustrate various properties of a reaction

Question 18

Arrhenius Equation

Answer 18

Mathematical relationship between a reaction’s rate constant, activation energy, and temperature

Question 19

Frequency Factor (A)

Answer 19

Proportionality constant in the Arrhenius equation, related to the relative number of collisions having an orientation capable of leading to product formation

Question 20

Reaction Mechanism

Answer 20

Stepwise sequence of elementary reactions by which a chemical change takes place

Question 21

Elementary Reaction

Answer 21

Reaction that takes place in a single step, precisely as depicted in its chemical equation

Question 22

Intermediates

Answer 22

Species produced in one step of a reaction mechanism and consumed in a subsequent step

Question 23

Molecularity

Answer 23

Number of reactant species involved in an elementary reaction

Question 24

Unimolecular Reaction

Answer 24

Elementary reaction involving a single reactant species

Question 25

Bimolecular Reaction

Answer 25

Elementary reaction involving two reactant species

Question 26

Termolecular Reaction

Answer 26

Elementary reaction involving three reactant species

Question 27

Rate-Determining Step (Rate-Limiting Step)

Answer 27

Slowest elementary reaction in a reaction mechanism; determines the rate of the overall reaction

Question 28

Homogeneous Catalyst

Answer 28

Catalyst present in the same phase as the reactants

Question 29

Heterogeneous Catalyst

Answer 29

Catalyst present in a different phase from the reactants, furnishing a surface at which a reaction can occur