Test 3 Flashcards
collision theory
A model that explains reaction rate as based on the number, every, and orientation of colliding particles.
Arrhenius equation
An equation that expresses the exponential relationship between temperature and the rate constant.
activation energy
The minimum energy with which molecules must collide to react.
effective collision
A collision in which the particles meet with sufficient energy and orientation that allows them to react.
frequency factor
The product of the collision frequency Z and an orientation probability factor p that is specific for a reaction.
transition state theory
A model that explains how the energy of reactant collisions is used to form a high-energy transitional species that can change to reactant or product
transition state
An unstable species formed in an effective collision of reactants that exists momentarily when the system is highest in energy and that can either form products or re-form reactants
reaction energy diagram
A graph that shows the potential energy of a reacting system as it progresses from reactants to products
reaction mechanism
A series of elementary tips that sum to the overall reaction and is consistent with the rate law
elementary reaction
A simple reaction that describes a single molecular event in proposed reaction mechanism
molecularity
The number of reactant particles involved in a elementary step
unimolecular reaction
An elementary reaction that involves the decomposition or rearrangement of a single particle.
bimolecular reaction
An elementary reaction involving the collision of two reactant species
rate-determining step
The slowest step in a reaction mechanism and therefore the step that limits the overall rate.
reaction intermediate
A substance that is formed and used up during the overall reaction and therefore does not appears int he overall equation
catalyst
A substance or mixture that increases the rate of a reaction without being used up in the process.
homogeneous catalyst
A catalyst that exists in the same phase as the reactants.
heterogeneous catalyst
A catalyst that occurs in a different phase from the reactants, usually a solid interacting with gaseous or liquid reactants.
hydrogenation
The addition of hydrogen to a carbon-carbon multiple bond to form a carbon-carbon single bond.
enzyme
A biological macromolecule that acts as a catalyst
active site
The region of an enzyme formed by specific amino acid side chains at which catalysis occurs.
equilibrium constant
The value obtained when equilibrium concentrations are substituted into the reaction quotient.
law of chemical equilibrium
The law stating that when a system reaches equilibrium a given temperature, the ratio of quantities that make up the reaction quotient has a constant numerical value
reaction of quotient
A ratio of terms for a given reaction consisting of product concentrations multiplied together and divided by reactant concentrations multiplied together, each raised to the power of their balancing coefficient. The value of Q changes until the system reaches equilibrium, at which point it equals K.
Le Chatelier’s principle
A principle stating that if a system in a stat of equilibrium is disturbed, it will undergo a change that shifts its equilibrium position in a direction that reduces the effect of the disturbance
Haber process
An industrial process used to form ammonia from its elements
hydronium ion
A proton covalently bonded to a water molecule
Arrhenius acid-base definition
A model of acid-base behavior in which an acid is a substance that has H in its formula and dissociates in water to yield H3O+, and a base is a substance that has OH in its formula and produces OH- in water
neutralization
Process that occurs when an H+ ion from an acid combines with an OH- ion from a base to from H2O
acid-dissociation constant
An equilibrium constant for the dissociation of an acid in H2O to yield the conjugate base and H3O+
autoionization
A reaction in which two molecules of a substance react to give ions
ion-product constant for water
The equilibrium constant for the auto ionization of water; equals to 1.00x10^-14 at 298K
pH
The negative common logarithm of H3O+
acid-base indicator
An organic molecule whose color is different in acid and in base and is used to monitor the equivalence point of a titration or the pH of a solution
Bronsted-Lowry acid-base definition
A model of acid-base behavior baed on proton transfer in which an acid and a base are defined, respectively, as species that donate and accept a proton.
proton donor
A substance that donates an H+ ion
proton acceptor
A substance that accepts and H+ ion
conjugate acid-base pair
Two species related to each other through the gain or loss of a proton; the acid has one more proton that its conjugate base.
polypro tic acid
An acid with more than one ionized proton.
base-dissociation constant
An equilibrium constant for the reaction of a base with H2O to yield the conjugate acid and OH-
Lewis acid-base definition
A model of acid-base behavior in which acids and bases are defined, respectively, as species that accept and donate an electron pair.
adduct
The product of a Lewis acid-base reaction characterized by the formation of a new covalent bond.
