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Chemistry > Rate Equations > Flashcards

Rate Equations Flashcards

1
Q

definition of rate of reaction

A

The change in concentration per unit of time

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2
Q

Definition of activation energy

A

The minimum energy required for a reaction to occur

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3
Q

Why does a higher temperature increase the rate of reaction

A

A higher temp more particles have E>Ea
Greater frequency of successful collisions

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4
Q

Why does a higher concentration/pressure increase the rate of reaction

A

more particles in a small amount of space
so more collisions between particles
so more frequent successful collisions

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5
Q

Why does breaking a solid into smaller particles increase the rate

A

increased surface area
more collisions between particles
greater frequency of successful collisions

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6
Q

What is a catalyst

A

a substance which increases rate of reaction
without being used up

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7
Q

How does a catalyst work

A

provides a reaction ruite

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8
Q

what is the x axis on a maxwell-boltzmann distribution curve

A

energy of particles

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9
Q

what is the y axis on a maxwell-boltzmann distribution curve

A

Number of particles

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10
Q

What does the area to the right of the Ea represent

A

particles which have enough energy to react

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11
Q

Why do the majority if chemical reactions start off with a fast rate of reaction and then slow down before it stops

A

initially, there is a high concentration of reactants so a large frequency of successful collisions
as reactants get used up, successful collisions become less frequent
once one or more reactants are used up, zero successful collisions

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12
Q

what does the gradient on a concentration vs time graph tell you

A

the rate of reaction at that specific moment in time

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13
Q

how to calculate the gradient

A

change in y / change in x

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14
Q

Rate α [X][Y]

A

equal effect on rate.

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15
Q

Rate α [X][Y]²

A

Y has greater effect on the rate

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16
Q

what is α the same as

A

k=

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17
Q

what is ‘k’

A

rate constant

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18
Q

What should units of k always end in and why

A

s-1 as it doesnt cancel out with anything

19
Q

What order are these?
Rate = k[X][Y]²

A

[X] - first order
[Y]² - second order

20
Q

What does zero order mean

A

Changing concentration of the reactant has no effect on the rate of reaction

21
Q

What does first order mean

A

Rate is directionally proportional to the concentration.
eg. doubling the concentration doubles the rate

22
Q

what does second order mean

A

Rate is proportionally to the square of the change in concentration
eg. doubling the concentration causes the rate to increase by 4 (2²)

23
Q

What is the only thing that affects k

A

temperature

24
Q

What does it mean when the rate vc conc graph is a horizontal line

A

zero order

25
Q

What does it mean when the rate vc conc graph is a straight diagonal line

A

1st order

26
Q

What does it mean when the rate vc conc graph is a line curving up

A

2nd order

27
Q

What is the Arrhenius equation

A

k=Ae^−Ea/RT

28
Q

What is K in the Arrhenius equation

A

Rate constant

29
Q

What is A in the Arrhenius equation

A

Arrhenius constant

30
Q

What is e in the Arrhenius equation

A

e on the calculator

31
Q

What is Ea in the Arrhenius equation

A

Activation energy

32
Q

What is R in the Arrhenius equation

A

gas constant (8.31)

33
Q

What is T in the Arrhenius equation

A

Temp in kelvin (+273)

34
Q

rearrangement of Arrhenius equation

A

ln(k)= ln A - Ea/RT

35
Q

what happens to the rate of reaction when you increase the temperature

A

the higher the temperature the faster the rate of reaction

36
Q

why is the higher the temperature the faster the rate of reaction becomes

A

the more kinetic energy each particle has
a greater proportion of particles has E>Ea
so greater frequency of successful collisions

37
Q

how can you use equation of a straight line with the Arrhenius equation

A

y = mx+c
Ln (k)= -Ea/RT + Ln A

38
Q

When using the equation of a straight line with the Arrhenius equation
what is y

A

Ln K

39
Q

When using the equation of a straight line with the Arrhenius equation
what is x

A

1/t

40
Q

When using the equation of a straight line with the Arrhenius equation
what is m

A

-Ea/R

41
Q

When using the equation of a straight line with the Arrhenius equation
what is c

A

Ln A

42
Q

what is m in the equation of a straight line

A

gradient

43
Q

what is c in the equation of a straight line

A

the height at which the line crosses the y -axis

Chemistry (38 decks)

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