Test 2 Flashcards

1
Q

chemical kinetics

A

the study of the rate of the chemical reaction and the factors that affect it

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2
Q

reaction rates can be measured by

A

the disappearing reactants or by the appearing products

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3
Q

average reaction rate

A

change in the measurable quantity of a chemical species/change in time

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4
Q

average reaction rate must be

A

positive

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5
Q

if finding the instantaneous rate

A

find the slope of the tangent line

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6
Q

determining measurable quantity: solids

A

-change in volume with a graduated cylinder, caliper, ruler
-change in mass with a balance

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7
Q

determining measurable quantity: liquid

A

-change in volume with a graduated cylinder, pipette
-change in mass with a balance

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8
Q

determining measurable quantity: solution

A

-take aliquots of solutions and perform titrations to calculate change in concentration
-take aliquots and use a spectrophotometer to measure color change(change in concentration)
-take aliquots and measure pH to see change in concentration

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9
Q

determining measurable quantity:gas

A

-change in volume with a eudiometer
-change in pressure with a manometer

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10
Q

factors that affect the rate: surface area

A

increase the surface area of solids, more molecules are exposed and can react

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11
Q

factors that affect the rate: concentration

A

-increasing the concentration of a solution allows more molecules to react
-increasing the concentration of gases increases the number of molecules reacting and increases the partial pressure of the gas

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12
Q

factors that affect the rate: temperature

A

-most significant factor that affects reaction rate
-increasing temperature increases the movement of reactants and applies force when they collide
-temperature is directly proportional to kinetic energy
-for most chemical reactions, raising the temperature 10 degrees C, will double the rate of reaction

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13
Q

factors that affect the rate: nature of reactants

A

differences in molecular size, electronegativity, pH, polarity, and other factors affect the rate of a reaction

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14
Q

factors that affect the rate: catalysts

A

-substance that speeds up a chemical reaction but does not get used up in a reaction

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15
Q

inhibitor

A

substance that slows down a chemical reaction by interacting with a reactant

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16
Q

state of matter rxn rate

A

solid<liquid<gas<solution

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17
Q

collision theory

A

states that the rate of a reaction depends on the number of collisions between reactants and fraction of collisions that produce a product

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18
Q

number of collisions between reactants

A

affected by temperature, concentration, and surface area

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19
Q

fraction of collisions that produce a product

A

affected by catalysts and temperature

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20
Q

factors that make effective collisions between reactants

A
  1. geometric shape of the reactants
  2. collision geometry(angle of collision)
  3. activation energy
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21
Q

activation energy

A

amount of energy required to make a reactant react

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22
Q

enough E must be provided to overcome

A

repulsion forces of electron clouds and break the bonds of reactants

23
Q

pH=

A

-log[H+]

24
Q

rate law

A

expression of reaction rate in terms of concentration of the reactants

25
Q

reaction rate=

A

K[A]^x[B]^y

26
Q

reaction order

A

the power that the concentration of each reactant is raised to that indicates that reactant’s effect on reaction rate

27
Q

reaction order requirements

A

-must be determined experimentally
-initial rates data must be used

28
Q

initial reaction rate

A

rate at the beginning of a chemical reaction when concentrations of reactants are highest

29
Q

zero order

A

when the concentration of the reactant is doubled, there is no effect on reaction rate

30
Q

1st order

A

when the concentration of the reactant is doubled, the reaction rate doubles

31
Q

2nd order

A

when the concentration of the reactant is doubled, the reaction rate quadruples

32
Q

overall reaction order

A

sum of the reaction orders of all the reactants in a reaction

33
Q

rate constant(k)

A

proportionality constant that relates the reaction rate to the concentration of the reactants

34
Q

k requirements

A

-must be determined using experimental data
-specific for a chemical reaction
-the units for k depend on the reaction order of the reactants
-changing concentrations of reactants has no change on the value of k
-determined at a specific temperature
-adding a catalyst increases k

35
Q

reaction mechanism

A

series of steps or smaller reactions that make up an overall reaction

36
Q

elementary process

A

step in a reaction mechanism

37
Q

catalyst

A

chemical species that is present at the beginning of a reaction, used up in a later reaction, and reformed by the end of a reaction

38
Q

intermediate

A

chemical species that forms in an elementary step and is used up before the reaction is completed

39
Q

molecularity

A

number of reactant species in an elementary step

40
Q

having 1 reactant

A

unimolecular

41
Q

having 2 reactants

A

bimolecular

42
Q

having 3 reactants

A

termolecular

43
Q

rate determining step(rds)

A

slowest elementary step that can be used to write a temporary rate law

44
Q

temporary rate law

A

rate law written without using initial rates data and must be verified experimentally; uses k’

45
Q

integrated rate law

A

expression of a reactant concentration as a direct function of time
-relate directly to overall reaction orders

46
Q

zero order integrated rate law

A

[A]= -Kt + [Ao]

47
Q

first order integrated rate law

A

ln[A]= -Kt + ln[Ao]

48
Q

second order integrated rate law

A

1/[A]= Kt + 1/[Ao]

49
Q

nth order integrated rate law

A

1/[A^n-1]= Kt + 1/[Ao^n-1]

50
Q

half-life(t1/2)

A

time it takes for 1/2 of a reactant concentration to be used up in a reaction
-directly related to the overall reaction

51
Q

zero order half-life

A

[Ao]/2K

52
Q

first order half-life

A

ln(2)/K

53
Q

second order half-life

A

1/K[Ao]

54
Q

each successive reaction order is

A

twice the amount of time as the previous order