AP Chem Chp. 14 Vocab

Question 1

Reaction Rate

Answer 1

The change in the concentration of reactants or products per unit of time. Avg rate = change in Concentration/ time

Question 2

Rate Constant

Answer 2

The constant K in the Rate Law. The magnitude of k changes with temperature and therefore determines how temperature affects rate. K = 1/ M*s

Question 3

Rate Law

Answer 3

Shows how rate depends on the concentration of reactants.

Question 4

Differential Rate Law

Answer 4

A form of the rate law which expresses how rate depends on concentration is called the differential rate law.

Question 5

Integrated Rate Law

Answer 5

Using an operation from calculus called integration. We can transform the rate law into an equation that relates the concentration of A at the start of the reaction [A]₀, to its concentration at any other time t, t.

Question 6

Reaction Order

Answer 6

The power to which the concentration of a reactant is raised in a rate law. (Section 14.3)

Question 7

Overall Reaction Order

Answer 7

The sum of the reaction orders of all the reactants appearing in the rate expression when the rate can be expressed as rate =k[A]a[B]b… . (Section 14.3)

Question 8

Zero-order reaction

Answer 8

Changing its concentration will have no effect on rate because any concentration raised to the power of zero equals 1.

Question 9

First Order Reaction

Answer 9

A reaction in which the reaction rate is proportional to the concentration of a single reactant, raised to the first power. (Section 14.4)

Question 10

Second Order Reaction

Answer 10

A reaction in which the overall reaction order (the sum of the concentration-term exponents) in the rate law is 2. (Section 14.4)

http://www.chem.purdue.edu/gchelp/howtosolveit/Kinetics/IntegratedRateLaws.html

Question 11

Half-life

Answer 11

The time required for the concentration of a reactant substance to decrease to half its initial value; the time required for half of a sample of a particular radioisotope to decay. (Sections 14.4 and 21.4)

Question 12

Activated Complex (also known as transition state)

Answer 12

The particular arrangement of atoms found at the top of the potential-energy barrier as a reaction proceeds from reactants to products. (Section 14.5)

Generally the lower the E_a the faster the reaction.

Question 13

Arrhenius Equation

Answer 13

Arrhenius equation

An equation that relates the rate constant for a reaction to the frequency factor, A, the activation energy, Ea, and the temperature, T: k = Ae^-E(a)/RT. In its logarithmic form it is written ln k = -Ea/RT + ln A. (Section 14.5)

Question 14

Frequency Factor

Answer 14

A term in the Arrhenius equation that is related to the frequency of collision and the probability that the collisions are favorably oriented for reaction. (Section 14.5) This is a constant!

Question 15

Reaction Mechanism

Answer 15

A detailed picture, or model, of how the reaction occurs; that is, the order in which bonds are broken and formed and the changes in relative positions of the atoms as the reaction proceeds. (Section 14.6)

Question 16

Elementary Reactions

Answer 16

A process in a chemical reaction that occurs in a single event or step. An overall chemical reaction consists of one or more elementary reactions or steps. (Section 14.6)

Question 17

Molecularity

Answer 17

The number of molecules that participate as reactants in an elementary reaction. (Section 14.6)

Question 18

Intermediate

Answer 18

A substance formed in one elementary step of a multistep mechanism and consumed in another; it is neither a reactant nor an ultimate product of the overall reaction. (Section 14.6)

Question 19

Unimolecular

Answer 19

An elementary reaction that involves a single molecule. (Section 14.6)

Question 20

Bi molecular

Answer 20

An elementary reaction that involves two molecules. (Section 14.6)

Question 21

Termolecular

Answer 21

an elementary reaction involving the simultaneous collision of any combination of three molecules, ions, or atoms

Question 22

Homogeneous Catalyst

Answer 22

a catalyst in the same phase as the reactants

Question 23

Heterogeneous Catalyst

Answer 23

the form ofcatalysis where the phase of the catalyst differs from that of the reactants

Question 24

Enzyme

Answer 24

macromolecular biological catalysts. They are responsible for thousands of metabolic processes that sustain life.

Question 25

Active site

Answer 25

a small port in an enzyme where substrate molecules bind and undergo a chemical reaction

Question 26

Substrate

Answer 26

a molecule upon which an enzyme acts

Question 27

Lock and Key Model

Answer 27

A model for enzyme-substrate interaction suggesting that the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another