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A2 Chemistry > Rates of Reaction (chapter 10 and 18) > Flashcards

Rates of Reaction (chapter 10 and 18) Flashcards

1
Q

how do you measure rate?

A

rate = change in concentration of reactant or product/time for change to take place

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2
Q

why do only a small % of collisions result in a reaction?

A

because they need to collide in the correct orientation and have sufficient energy to overcome activation energy

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3
Q

what happens if the frequency of collisions increase?

A

the rate of reaction also increases but the % of successful collisions stay the same

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4
Q

how do you increase the rate of a reaction?

A

increase the concentration

increase the temperature

increase the SA

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5
Q

what effect does increasing the concentration of reagents have?

A

increases the number of reactant particles in a given volume which means they’re closer together and collide more frequently, resulting in more effective collisions in a given time (same applies to pressure)

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6
Q

definition of orders of reaction

A

the power to which the concentration of the reactant is raised in the rate equation

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7
Q

what does a rate-concentration graph look like in a 0 order reaction?

A

a straight horizontal line

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8
Q

what does a concentration-time graph look like in a 0 order reaction?

A

a straight negative correlation line

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9
Q

what does a concentration-time graph look like in a 1st order reaction?

A

curved with constant half life

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10
Q

what does a rate-concentration graph look like in a 1st order reaction?

A

straight diagonal line going through the origin

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11
Q

what does a concentration-time graph look like in a 2nd order reaction?

A

deep curve

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12
Q

what does a rate-concentration graph look like in a 2nd order reaction?

A

a diagonal positive correlation

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13
Q

what is the rate equation?

A

shows the mathematical relationship between concentrations of reactants and reaction rates

rate = k [A]n

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14
Q

what’s the rate determining step?

A

a reaction may proceed in several steps (reaction mechanism) however only the slowest step controls the overall rate

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15
Q

what effect does increasing the surface area have on rate?

A

allows more collisions to occur

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16
Q

what effect does increasing the temperature have on rate?

A

this ALWAYS increases the rate as the particles have more kinetic energy so they move more quickly which increases the amount of collisions in a given temperature

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17
Q

what effect does increasing the temperature have on equilibrium?

A

shifts the boltzmann distribution curve to the right - increasing the proportion of particles that exceed Ea
particles move faster and collide more frequently

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18
Q

what’s the arrhenius equation?

A

shows the exponential relationship between the rate constant k and temperature

k=Ae -EaRT

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19
Q

what’s the pre-exponential factor?

A

accounts for frequency of collisions with the correct orientation

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20
Q

what’s the exponential factor?

A

proportion of molecules that have sufficient energy for a reaction to take place

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21
Q

what are 2 methods of following a progress of a reaction?

A

monitoring volume of gas produced

monitoring loss of mass of reactants

22
Q

effect of a positive catalyst?

A

a substance that increases the rate of reaction by providing an alternative pathway with a lower Ea but remains itself unchanged

23
Q

what’s a homogeneous catalyst?

A

has the same physical state as reactants and react with reactants to form an intermediate which breaks down to give the product

24
Q

what’s a heterogenous catalyst?

A

has a different physical state and the reactant molecules are absorbed onto the surface of the catalyst then the product molecules leave the surface by deabsorbtion

25
Q

what is the economic importance of catalysts?

A

they speed up the reaction meaning more of the desired product can be produced quickly for sale and less energy is needed

this energy usually comes from high temperatures so reducing this reduces costs to manufacturer, reduces amount of fossil fuels and amount of C02 produced

higher percentage yield and atom economy

26
Q

how do you measure rate?

A

rate = change in concentration of reactant or product/time for change to take place

27
Q

why do only a small % of collisions result in a reaction?

A

because they need to collide in the correct orientation and have sufficient energy to overcome activation energy

28
Q

what happens if the frequency of collisions increase?

A

the rate of reaction also increases but the % of successful collisions stay the same

29
Q

how do you increase the rate of a reaction?

A

increase the concentration

increase the temperature

increase the SA

30
Q

what effect does increasing the concentration of reagents have?

A

increases the number of reactant particles in a given volume which means they’re closer together and collide more frequently, resulting in more effective collisions in a given time (same applies to pressure)

31
Q

definition of orders of reaction

A

the power to which the concentration of the reactant is raised in the rate equation

32
Q

what does a rate-concentration graph look like in a 0 order reaction?

A

a straight horizontal line

33
Q

what does a concentration-time graph look like in a 0 order reaction?

A

a straight negative correlation line

34
Q

what does a concentration-time graph look like in a 1st order reaction?

A

curved with constant half life

35
Q

what does a rate-concentration graph look like in a 1st order reaction?

A

straight diagonal line going through the origin

36
Q

what does a concentration-time graph look like in a 2nd order reaction?

A

deep curve

37
Q

what does a rate-concentration graph look like in a 2nd order reaction?

A

a diagonal positive correlation

38
Q

what is the rate equation?

A

shows the mathematical relationship between concentrations of reactants and reaction rates

rate = k [A]n

39
Q

what’s the rate determining step?

A

a reaction may proceed in several steps (reaction mechanism) however only the slowest step controls the overall rate

40
Q

what effect does increasing the surface area have on rate?

A

allows more collisions to occur

41
Q

what effect does increasing the temperature have on rate?

A

this ALWAYS increases the rate as the particles have more kinetic energy so they move more quickly which increases the amount of collisions in a given temperature

42
Q

what effect does increasing the temperature have on equilibrium?

A

shifts the boltzmann distribution curve to the right - increasing the proportion of particles that exceed Ea
particles move faster and collide more frequently

43
Q

what’s the arrhenius equation?

A

shows the exponential relationship between the rate constant k and temperature

k=Ae -EaRT

44
Q

what’s the pre-exponential factor?

A

accounts for frequency of collisions with the correct orientation

45
Q

what’s the exponential factor?

A

proportion of molecules that have sufficient energy for a reaction to take place

46
Q

what are 2 methods of following a progress of a reaction?

A

monitoring volume of gas produced

monitoring loss of mass of reactants

47
Q

effect of a positive catalyst?

A

a substance that increases the rate of reaction by providing an alternative pathway with a lower Ea but remains itself unchanged

48
Q

what’s a homogeneous catalyst?

A

has the same physical state as reactants and react with reactants to form an intermediate which breaks down to give the product

49
Q

what’s a heterogenous catalyst?

A

has a different physical state and the reactant molecules are absorbed onto the surface of the catalyst then the product molecules leave the surface by deabsorbtion

50
Q

what is the economic importance of catalysts?

A

they speed up the reaction meaning more of the desired product can be produced quickly for sale and less energy is needed

this energy usually comes from high temperatures so reducing this reduces costs to manufacturer, reduces amount of fossil fuels and amount of C02 produced

higher percentage yield and atom economy

A2 Chemistry (7 decks)

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