29 terms

Chapter 19: Reaction Rates and Equilibrium

Measures the speed of any change that occurs with in an interval of time.
Activation Energy
The minimum amount of energy that particles must have in order to react.
Activated Complex
The arrangement of atoms at the peak of the activation-energy barrier.
Transition State
The activated complex.
Factors Affecting Reaction Rates
Temperature, concentration, particle size, catalysts
A substance that increases the rate of a reaction without being used up itself during the reaction.
A substance that slows down a chemical reaction
Reversible Reactions
Can go in either direction under different circumstances and are represented with paired arrows
Chemical Equilibrium
a state of balance in which the rate of a forward reaction equals the rate of the reverse reaction and the concentrations of products and reactants remain unchanged
Equilibrium Position
the relative concentrations of reactants and products of a reaction that has reached equilibrium; indicates whether the reactants or products are favored in the reversible reaction
Le Chatelier's Principle
States that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.
Equilibrium Constant (Keq)
the ratio of product concentrations to reactant concentrations at equilibrium, with each concentration raised to a power equal to the number of moles of that substance in the balanced chemical equation
Free Energy
energy that is available to do work
Spontaneous Reactions
reactions that occur naturally and that favor the formation of products at the specified conditions
Non-Spontaneous Reactions
a reaction that does not favor the formation of products at the specified conditions( reactants)
a measure of the disorder of a system
Law of Disorder
states that spontaneous processes always proceed in such a way that the entropy of the universe increases
Standard Entropy
The entropy at a specified temperature (usually 298 K) for 1 mol of a pure substance at 1 atmosphere pressure.
Gibbs free-energy
The energy in a system that can be used to drive chemical reactions. If the change in free energy of a reaction (Delta G, the free energy of the products minus the free energy of the energy of the reactants) is negative, the reaction will occur spontaneously.
Rate Law
an expression relating the rate of a reaction to the concentration of the reactants
Specific rate constant
a proportionality constant relating the concentrations of reactants to the rate of the reaction
First-order reaction
the reaction rate is directly proportional to the concentration of only one reactant
Elementary Reaction
a reaction in which reactants are converted to products in a single step
Reaction Mechanism
the step-by-step sequence of reactions by which the overall chemical change occurs
a substance formed during a chemical process before the desired product is obtained