Textbook Chapter 12- Kinectics

Question 1

rate of a chemical reaction

Answer 1

the rate of a chemical reaction is a measure of how much reactant is consumed, or how much product is produced, by the reaction in a given amount of time.

Question 2

rate expression

Answer 2

the mathematical representation of the change in species concentration over time

Question 3

reaction rates (3)

Answer 3

the change in the amount of a reactant or product per unit time.

Reaction rates are therefore determined by measuring the time dependence of some property that can be related to reactant or product amounts.

by convention positive

Question 4

relative rates of reaction (3)

for homogenous reactions…

Answer 4

all related simply to one another according to the reaction stoichiometry.

For homogeneous reactions, both the reactants and products are present in the same solution and thus occupy the same volume, so the molar amounts may be replaced with molar concentrations:

Question 5

factors affecting reaction rates (5)

Answer 5

concentration
temperature
catalyst
physical state (more sa is faster)
nature of participating substances

Question 6

When reactants are in different physical states, or phases (solid, liquid, gaseous, dissolved), the reaction takes place only at

Answer 6

the interface between the phases

Question 7

rate law

Answer 7

mathematical expressions that describe the relationship between the rate of a chemical reaction and the concentration of its reactants.

Question 8

the forms m and n in rate law can be an what they are (2)

Answer 8

reaction orders

can be positive, negative, fraction or 0

Question 9

K (2)

what is it independent off and dependant off

Answer 9

rate constant

independent of the reactant concentrations but does vary with temp and pressure

Question 10

how is k m n determined in rate law

Answer 10

must be determined experimentally by observing how the rate of a reaction changes as the concentrations of the reactants are changed.

Question 11

instantaneous rate (3)

Answer 11

a snapshot/rate at a specific time

defined as the slope of the tangent to the concentration vs time graph

the derivative of the curve at time t

Question 12

the higher the order of the reactant

Answer 12

the more effect it has on the reaction

Question 13

rate order of 0 indicates that+in rate equation (2)

Answer 13

the reactant has no affect on the rate

no need to write in rate law

Question 14

method of initial rates (2)

Answer 14

measuring reaction rates for multiple experimental trials carried out using different initial reactant concentrations

An approach to determine rate law

Question 15

How to find rate law 2 method with a table:

Answer 15

1. find the row where the first reactant is constant but the second ist. See how the change in the second causes the change in the reaction rate (diving and see how much larger after the second reactant is doubled or sm)
   do the same for first reactant
2. rate 3/rate2=k[1][2]/k[1][2]

and use the exponent which is m, n to find the value.

Question 16

Integrated rate law (2)

+what you can use it for/Ex

Answer 16

relates the concentrations of reactants and time

We can use an integrated rate law to determine the amount of reactant or product present after a period of time or to estimate the time required for a reaction to proceed to a certain extent. For example, an integrated rate law is used to determine the length of time a radioactive material must be stored for its radioactivity to decay to a safe level.

Question 17

deferential rate law integrated with respect to time=

not equation just general***

Answer 17

equation that relates the amount of reactant/product present in a rxn mixture to the elaspes time of the rxn

Question 18

difference between differential rate law and integrated

Answer 18

The differential rate law tells you how the rate of a reaction depends on the concentration of reactant(s). The integrated rate law tells you how the concentration of reactant(s) depends on time

Question 19

Integration of the rate law for a simple first-order reaction (rate = k[A]) results in an equaton……
+what is it?

Answer 19

in an equation describing how the reactant concentration varies with time:

Question 20

integration of first order rate law…this equation may be rearranged to other formats, including direct and indirect proportionalities and linear dependance: (3)

Answer 20

Question 21

graphing linear format of first degree+what if not straight line+formula (2)

Answer 21

A plot of ln[A]t versus t for a first-order reaction is a straight line with a slope of −k and a y-intercept of ln[A]0. If a set of rate data are plotted in this fashion but do not result in a straight line, the reaction is not first order in A.

Question 22

According to the linear format of the first-order integrated rate law, the rate constant is given by

*not experimental execution u dumb

Answer 22

the negative of this plot’s slope.

Question 23

what’s the axis for characteristic kinectic plot of first degree for integrated

Answer 23

ln[A]t vs t

Question 24

Charactertosoc kinectic plot of secind degree

Answer 24

1/[A]t. vs t

Question 25

rate unit in the rate law always equal to

Answer 25

mol/ls so M/s=rate law units

Question 26

rate law constant units between M(mol/L) and t *M

Answer 26

M exponent keeps decreasing

Question 27

you know an integrated rate law is second order reaction is___+line plotting equation

Answer 27

the plotted is a striaght line.

Question 28

half-life of a reaction (t1/2)

Answer 28

the time required for one-half of a given amount of reactant to be consumed

Question 29

zero order half life depends on | +equation

Answer 29

initial concentration and rate constant

Question 30

First order half life | dependent on/not dependent on/ equation

Answer 30

depends only on K, independent on the concentration

Question 31

Second order half life | formula, depends on

Answer 31

Depends on inital concentration and rate constant

Question 32

In first order reactions what is the relationship between fast/short reactions and k value and half life?

Answer 32

Faster reactions exhibit larger rate constants and correspondingly shorter half-lives. Slower reactions exhibit smaller rate constants and longer half-lives.

Question 33

For second order reaction what happens to half life as reaction proceeds?

Answer 33

the half-life increases as the reaction proceeds because the concentration of reactant decreases.

Question 34

half-life of a zero-order reaction and initital concentration relationship

Answer 34

The half-life of a zero-order reaction increases as the initial concentration increases.

Question 35

which rate order's integrated rate law linear plot slope is positive?

Answer 35

2nd

Question 36

What is the three thing collision theory is based on?

Answer 36

1. The rate of a reaction is proportional to the rate of reactant collisions 2. The reacting species must collide in an orientation that allows contact between the atoms that will become bonded together in the product. 3. The collision must occur with adequate energy to permit mutual penetration of the reacting species’ valence shells so that the electrons can rearrange and form new bonds (and new chemical species).

Question 36

What is the three thing collision theory is based on? (3)

Answer 36

1. The rate of reaction is porprotional to the rate of reactant collisions 2. The reacting species must collide in an orientation that allow contact between the atoms that will become bonded together in the product 3. The collision must occur with adequate energy to permit mutual penetration of reacting species valence shell so that the electron can rearrange ad form new bonds

Question 37

activated complex/transition state

Answer 37

an unstable species, very short lived and usually undetectable by most analytical instruments.

Question 38

Explain to me the relationship between activation energy and kinectic energy

Answer 38

If the activation energy is much larger than the average kinetic energy of the molecules, the reaction will occur slowly since only a few fast-moving molecules will have enough energy to react. If the activation energy is much smaller than the average kinetic energy of the molecules, a large fraction of molecules will be adequately energetic and the reaction will proceed rapidly

Question 39

reaction diagram general

Answer 39

Used in chemical kinetics to illustrate various properties of the reaction of interest. Viewing the diagram from left to right, the system initially comprises reactants only, A + B. Reactant molecules with sufficient energy can collide to form a high-energy activated complex or transition state. The unstable transition state can then subsequently decay to yield stable products, C + D.

Question 40

activation energy Ea

Answer 40

energy difference between the reactants and transition state

Question 41

enthalpy change | +what is exothermic?

Answer 41

the energy difference between the reactants and products ΔH<0 is exothermic

Question 42

Arehenius equation+equation | what R, A e means

Answer 42

relates the activation energy and the rate constant R is the ideal gas constant, which has a value 8.314 J/mol/K, T is temperature on the Kelvin scale, Ea is the activation energy in joules per mole, e is the constant 2.7183, and A is a constant called the frequency factor, which is related to the frequency of collisions and the orientation of the reacting molecules.

Question 43

frequency factor A +what does increase probability result in

Answer 43

reflects how well the reaction conditions favor properly oriented collisions between reactant molecules. An increased probability of effectively oriented collisions results in larger values for A and faster reaction rates.

Question 44

The exponential term, e−Ea/RT,

Answer 44

describes the effect of activation energy on reaction rate

Question 45

A lower activation energy results in a

Answer 45

greater fraction of adequately energized molecules and a faster reaction.

Question 46

The exponential term also describes the effect of temperature on reaction rate....How?

Answer 46

A higher temperature represents a correspondingly greater fraction of molecules possessing sufficient energy (RT) to overcome the activation barrier (Ea)

Question 47

Large value for Rate constant equals...... | rate...

Answer 47

This yields a greater value for the rate constant and a correspondingly faster reaction rate.

Question 48

A convenient approach for determining Ea for a reaction involves | *verbal word no number/equations

Answer 48

the measurement of k at two or more different temperatures and using an alternate version of the Arrhenius equation that takes the form of a linear equation

Question 49

What is the linear form of the arrhenius equation? | +what does each mean? +what is the x and y axis

Answer 49

A plot of ln k versus 1/T is linear with a slope equal to -Ea/R and a y-intercept equal to ln A.

Question 50

Two mathmatical/graphical rearrangement convenient approach for determining Ea for a reaction involves (2)

Answer 50

1. graph the lnK vs 1/T graph and find slope and make it equal to -Ea/R 2. point slope formula : lnK2-lnK1=-Ea/R(1/T2-1/T1) ln (K1/K2)=Ea/R (1/T2-1/T1)

Question 51

Reaction mechanism/reaction path (2) | +ex

Answer 51

A reaction mechanism is the sequence of elementary steps by which a chemical reaction occurs. ex: ozone decomposition

Question 52

Elementary steps | they occur....... and must.....

Answer 52

each steps in a reaction mechanism These elementary reactions occur precisely as represented in the step equations, and they must sum to yield the balanced chemical equation representing the overall reaction

Question 53

Intermediates

Answer 53

species produced in one step and consumed in a subsequent step

Question 54

rate law for an elementary reaction may be

Answer 54

derived directly from the balanced chemical equation describing the reaction 2A + B → products is rate = k[A]²[B].

Question 55

rate-determining step | What does it limit +what does it determine?

Answer 55

The slowest step in a reaction mechanism The rate-determining step limits the overall rate and therefore determines the rate law for the overall reaction.

Question 56

molecularity

Answer 56

number of reactant species For ex: molecularity of 1

Question 57

unimolecular reaction+ex

Answer 57

involves the reaction of a single reactant species to produce one or more molecules of product:

Question 58

bimolecular reaction | + what are the two types?

Answer 58

involves two reactant species

Question 59

termolecular reaction+ex | +Why are they uncommon?

Answer 59

the simultaneous collision of three atoms, molecules, or ions. Termolecular elementary reactions are uncommon because the probability of three particles colliding simultaneously is less than one one-thousandth of the probability of two particles colliding.

Question 60

Rate limiting step | +what it does

Answer 60

The slowest step of the reaction that will limit the rate at which the overall reaction occurs

Question 61

a reversible reaction is at equilibrium when

Answer 61

the rates of the forward and reverse processes are equal

Question 62

How do you find the concentration of intermediates

Answer 62

Question 63

catalyst | +how do they do this (2)

Answer 63

a substance that can increase the reaction rate without being consumed in the reaction by providing an alternative reaction mechanism with a lower activation energy+provide a reaction path whose rate determining step is faster (lower Ea).

Question 64

Homogenous catalyst+ states+one important thing about it

Answer 64

presennt int the same phase as the reactants, interacts with the reactants to form an intermediate substance which then decomposes or reacts with another reactant in one or more steps to regenerate the original catalyst and form product. +participates in chemical reaction but is never consumed

Question 65

heterogenous catalyst | +process of how it works

Answer 65

a catalyst that is present in a different phase (usually solid) than the reactants. Generally function by furnishing an active surface upon which a reaction can occur. -gets absorbed andthe bonds can get weakened and go thru reactions. In the end it gets desorped.

Question 66

integrated rate law about half life time rate between the diff order no math or anything just decrease or increase

Answer 66

0th order- half life time decreases 1st order- half life time remain costant 2nd order- half life time increases

Question 67

how to solve for A

Answer 67

Point slope form of arrhenius to find EA and sub back to arrhenius orginal to find A

Question 68

how are catalyst shown in a chemical equation?

Answer 68

above the arrow