rates of reaction

Question 1

chemical kinetics

Answer 1

the study of rates of chemical reactions and the factors that influence these rates

Synonymous with rates of reaction

Question 2

HOW WILL WE MEASURE REACTION RATES?

Answer 2

The rate of appearance of product or the rate of disappearance of reactants

o Units are mol/L/s

Question 3

Reaction rate

Answer 3

number of atoms, ions, or molecules that react in a given time to form products

Question 4

COLLISION THEORY

Answer 4

atoms, ions, and molecules can react to form products when they collide with one another, provided that the colliding particles have enough kinetic energy

collision between reactant molecules must have the correct orientation in order for a chemical reaction to take place

Question 5

activated complex

Answer 5

peak of the activation energy barrier is a very unstable formation of an arrangement of atoms

it is also called the transition state as it has equal chance to become products or return to original states

o lifetime is about 10^-13s

Question 6

FACTORS THAT IMPACT CHEMICAL KINETICS

Answer 6

Concentration (for homogeneous reactions) or particle size (for heterogeneous reactions)

Temperature

Prescence of a catalyst

Nature of the reactants

Question 7

inhibitor

Answer 7

A substance that interferes with catalysis

Question 8

Instantaneous Rate

Answer 8

the reaction rate calculated at a single time during the course of a reaction (oh god derivatives)

Question 9

Initial Rate

Answer 9

The reaction rate calculated at the beginning, prior to any substantial chemical reactions. No interference!

Question 10

reaction mechanism

Answer 10

the step by step sequence of elementary reactions by which overall chemical change occurs (for complex reactions!!)

Question 11

Elementary Step

Answer 11

each step in a reaction mechanism

Question 12

reaction intermediates

Answer 12

Substances that are formed in one step of the reaction mechanism and used up in a later step

Question 13

rate determining step

Answer 13

slowest step in a reaction, basically determines how fast the reaction goes

basically the one with the highest activation energy

Question 14

activation energy

Answer 14

minimum energy that colliding particles must have in order to react

POTENTIAL ENERGY!!

explains why some exothermic reactions do not occur at room temperature

Question 15

maxwell-Boltzman Distribution

Answer 15

The distribution of speeds/energies in a chemical reaction.

can use to show the threshold energy

Question 16

threshold energy

Answer 16

The minimum energy that molecules must have in order to break bonds

KINETIC ENERGY!!

For typical reactions, the threshold energy is out in the tail section of the distribution curve

Question 17

where should the threshold energy barrier move for a faster reaction or slower reaction?

Answer 17

move to the LEFT for a faster reaction

move to the RIGHT for a slower reaction

Question 18

what kind of threshold energies would very fast reactions have?

Answer 18

LOWER ones

Question 19

what kind of threshold energies would very slow reactions have?

Answer 19

HIGHER ones

Question 20

10c temperature change impact on M-B distribution?

Answer 20

it can often double a reaction rate

Average KE (temperature) increases only slightly, the portion to the right of the threshold energy barrier doubles in size

Question 21

catalyst impact on potential graph/reaction?

Answer 21

provides an alternative route for the reaction with a lower!!!! Activation energy!!

on a graph, it lowers the thingy for activation energy

It is important to remember that a catalyst doesn’t actually lower the activation energy

It provides an alternative reaction pathway

Question 22

Homogenous catalysts

Answer 22

are in the same phase as the reactants

They work by providing a new mechanism in which they react in an early step and are recreated in a later step

No net loss of catalyst!!!

Question 23

Heterogenous catalysts

Answer 23

are in a different phase than the reactants

Most of the time they be solids and the reactants flow over the surface

Question 24

how do catalysts work

Answer 24

Reactant molecules are absorbed onto the catalyst surface

The molecules bonds are weakened as they stick to the surface

Also!! Molecules are held in a position so that when other molecules collide with them, chances are better off having an effective collision

Think of GOLF!! Teeing a ball up to get a better shot at it! Compared to trying to hit it out of the rough or a sand trap!

Question 25

elementary reaction

Answer 25

reactions that only need one step!

Question 26

Activated Complex/Transition State Theory

Answer 26

Rates of reaction can be studied by examining activated complexes!

The activated complexes can convert into products, and kinetic theory can be used to calculate the rate of this conversion.

(from wikipedia^^)
basically it wants to explain activated complexes and how reactions occur

ANYWAY JUST THINK OF maxwell-Boltzman Distribution AND THRESHOLD ENERGY

Question 27

what is a specific rate constant (k) for a reaction?

Answer 27

number that relates concentration of a reaction to the rate of reaction

Question 28

how do you determine the actual kinetic order of a reaction?

Answer 28

by the experiment! collect data!

Question 29

effective collision

Answer 29

reaction where there IS a change!

Question 30

ineffective collision

Answer 30

reaction where nothing happens, the products are the same as the reactants