Chpt 14: Chemical Kinetics Flashcards Preview

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Flashcards in Chpt 14: Chemical Kinetics Deck (35):
1

Chimical Kinetics

study of and discussion of how reactions progress, particularly with regard to reaction rates

2

4 factors that effect chemical reaction rates

1. Physical state of reactants
2. concentration
3. Temperature
4. Presence of catalysts

Surface area of atoms makes a difference, too. Thanks, Khan!

3

Chemical reaction rates

Delta concentration over time

Exp. molarity/time or M/s

4

Tangent line????

????

5

Rate law

The rate of a rxn expressed in terms of the impact that the concentration of its REACTANTS has on its rate

Formula: rate = k[reactant1]^m[reactant 2]^n...

6

Reaction order

exponents in a rate law (that represent the moles of each component)

Must be determined experimentally

7

Beer's Law

Says the absorption of radiation (at a given wavelength) by a substance is proportional to the solution's concentration

We used this concept with the spectroscope in biology class when she shined the light on the reaction to measure the enzyme activity in the starch

8

First-order rxn

A rxn whose rate is proportional to the concentration of a single reactant raised to the first power

Exp. rate = k[A]

9

Second-order rxn????

A rxn whose overall 'reaction order' = 2

10

Zero-order rxn

A rxn whose 'overall reaction order' = 0

11

Activated complex

The region between/around molecules/compounds that are about to bond in a reaction

Occurs when the rxn molecules/compounds are in a high energy/transition state; about to react

12

High energy/transition state (of rxn)???

The excited sate a rxn is in right before its molecules/compounds start reacting

13

Activation energy

Minimum energy required for a rxn to start

Potential energies of reactants starts relatively high, but goes lower/more negative when they bind to other reactants; Initiation of this process requires (activation) energy

14

Rxn catalyst

Makes a rxn happen faster or lowers the amount of E needed to progress the rxn

15

Positive catalyst

Speeds up rxns (by lowering the activation energy required)

16

Negative catalysts

Slow down rxns

17

Collision model (of chemical kinetics)

The idea that chemical rxns occur bc of collisions between molecules

Explains why rxn rates go up as temp goes us

18

Arrhenius Equation

Relates quantities of collision model

Expresses the relationship between temp and the rate constant "k"

19

Rxn mechanism

Describes the steps that occur over the course of a rxn

20

Elementary rxns

The individual (intermediate?) steps of a reaction mechanism, which each have their own rate laws based on the number of molecules present

21

Molecularity

The number of molecules present during a given step/elementary rxn of an overall chemical rxn

22

3 types of molecularity

1. Unimolecular
2. Bimolecular
3. Termolecular

23

Unimolecular elementary rxns

Rxn involving one reactant molecule

24

Bimolecular molecularity

Rxn involving 2 reactant molecules

25

Termolecular molecularity

Rxn involving 3 reactant molecules

26

Intermediate 'product'

Temporary/intermediate product created during a former elementary rxn/step that gets consumed in the process of the rxn progressing to the next elementary rxn/step

27

Rate determining step (of a rxn)

The slowest in a series of rxn elementary steps

Sets the pace for the entire over arching rxn; often involves intermediate 'products'

28

Homogenous catalyst

A rxn catalyst that is in the same phase as the reactants

29

Heterogeneous catalyst

A rxn catalyst that is in a different phase than the reactants

30

Adsortion

When reacting molecules bind to the surface of a catalyst

This lowers the activation energt

31

Enzymes

Bx as catalysts/facilitate 'catalysis' in living things

32

Substrates

What you call the reactants that enzymes engaged in catalysis act on

33

Active site

The complex on an enzyme where catalysis is facilitated

34

Lock and Key model (for enzymes)

The idea that substrates bind to enzymes at specific active sites in order to initiate the rxn

35

Overall reaction order

The sum of all of a reactions' components' exponents