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A Level Chemistry OCR B > Chemical Industry > Flashcards

Chemical Industry Flashcards

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1
Q

what is rate of reaction?

A

the change in the amount of reactants or products per unit time (normally per second)

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2
Q

What is the general equation for rate?

A

Rate = amount of reactant used/ product made / time

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3
Q

what is the rate constant - and what does it tell us

A

k

units vary so have to work them out

the bigger it is the faster the rate of reaction

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4
Q

what are orders of reaction?

A
  • tells you how the reactant concentration affects the rate
  • rate is proportional to [A]
  • need order of reaction with respect to reactant
  • reaction also has an overall order which is the sum of the orders of the different reactants
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5
Q

how do you find the order w.r.t a reactant?

A

look at how each reactant affects the rate one by one

if [A] changes and rate stays the same: 0 order w.r.t [A]

if [A] doubles and rate double (proportional): 1st order w.r.t [A]

if [A] double and the rate is 2^2 faster (triples is 3^2 faster): 2nd order w.r.t [A]

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6
Q

how does temperature affect the rate constant?

A

if you increase temperature you will increase the rate of reaction

  • more kinetic energy
  • particle speed up and are more likely to collide
  • have the right activation energy to react so greater proportion will have enough energy to react
    at a higher temperature the reaction will have a higher rate constant
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7
Q

What is half life?

A

The time taken for a reactant to halve in quantity.

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8
Q

What is the effect of adding a catalyst on the equilibrium constant?

A

None

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9
Q

What is the effect of increasing the temperature of a dynamic equilibrium on the position of equilibrium?

A

Will move it in the endothermic direction.

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10
Q

What is the effect of increasing the pressure of a dynamic equilibrium on the position of equilibrium?

A

It’ll move the position of equilibrium towards the side with the fewest moles of gas.

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11
Q

What is the effect of increasing the concentration of a reactant in a dynamic equilibrium on the position of equilibrium?

A

It will move to the right

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12
Q

What is the effect of increasing the pressure of a dynamic equilibrium on the equilibrium constant?

A

None

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13
Q

What is the effect of adding a catalyst on the position of equilibrium?

A

None

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14
Q

What is the effect of increasing the temperature of a dynamic equilibrium on the equilibrium constant?

A

Will increase if the forward reaction is endothermic, decrease if it’s exothermic.

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15
Q

What is the effect of increasing the concentration of a reactant in a dynamic equilibrium on the equilibrium constant?

A

None

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16
Q

How could you find the equilibrium concentration experimentally?

A

If it’s coloured, use colorimetry. If one of the sides contains an acid/alkali, use a pH meter. Then use the Kc equation to calculate its value.

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17
Q

How to follow the rate of reaction - experimental methods?

A
  • pH measurement
  • gas volume
  • loss of mass
  • colour change
  • titration
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18
Q

Give an example of an initial rate experiment

A

Clock reactions

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19
Q

What are clock reactions?

A

measure how much time takes for a set amount of product to form changes as you vary concentrations of one of the reactants

has an easily observable end point - a colour change - that tells you when desired product is formed

the quicker the clock reaction finishes the faster the initial rate

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20
Q

what does the arrhenius equation link?

A

an equation that links the rate constant and activation enthalpy

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21
Q

arrhenius equation - as the activation energy gets bigger…..

A

…K gets smaller

22
Q

arrhenius equation - a large Ea means….

A

…a slow rate

not many particles have enough energy to react
so only a few collisions will result in a reaction

23
Q

arrhenius equation - as temperature rises….

A

…K increases

24
Q

what is the rate determining step?

A

the slowest step in a multistep reaction

the overall rate is determined by this

25
Q

how can you use the rate equation to determine the rate determining step?

A

if a reactant appears in the equation, it must affect the rate
- so this reactant or something made in it must be in the rate determining step

if a reactant doesn’t appear in the rate equation, then it isn’t involved in the rate determining step

26
Q

Does the rate determining step need to be the first step in a mechanism?

A

No

27
Q

what does the order w.r.t a reactant show about the rate determining step?

A

shows the no. of molecules of that reactant that are involved in the rate-determining step

28
Q

What are the formulae for the oxides of nitrogen?

A

NO, N2O and NO2

29
Q

Name NO

A

nitrogen(II) oxide or nitrogen (mon)oxide

30
Q

How are oxides formed in the nitrogen cycle?

A

N2 and a multiple of O2

31
Q

How are nitrate(III) ions formed in the nitrogen cycle?

A

ammonium ions + O2

32
Q

What is produced when Devarda’s alloy reacts with a nitrate(V)?

A

NH3 gas, H2O and Al(OH)4-

33
Q

How is nitrogen gas formed in the nitrogen cycle?

A

Nitrate(V) ions + H+ + e

34
Q

What is Devarda’s alloy?

A

An alloy made from aluminium and copper

35
Q

How are ammonium ions formed in the nitrogen cycle?

A

ammonia + H+

36
Q

What is the appearance of NO2?

A

Brown gas

37
Q

What is the formula of an ammonium ion?

A

NH4+

38
Q

What is the formula of ammonia?

A

NH3

39
Q

Describe the bonding in N2

A

Triple covalent bond

40
Q

What is the appearance of N2O?

A

Colourless gas

41
Q

Name N2O

A

Nitrogen(I) oxide or dinitrogen (mon)oxidide

42
Q

How are nitrate(V) ions formed in the nitrogen cycle?

A

Nitrate(III) + H2O

43
Q

What is the appearance of NO?

A

Colourless gas

44
Q

Name NO2

A

Nitrogen(IV) oxide or nitrogen dioxide

45
Q

How is ammonia formed in the nitrogen cycle?

A

N2 and H2 react

46
Q

Which molecules and ions take part in the nitrogen cycle?

A

Ammonia, nitrogen, water, oxygen, hydrogen, nitrate(V), nitrate(III), ammonium

47
Q

What is the test for nitrate(V) ions?

A

Add Devarda’s alloy and NaOH. Heat. Test for the ammonia gas released with damp red litmus paper —> blue

48
Q

What is the formula of a nitrate(V) ion?

A

NO3-

49
Q

What is the formula of nitrate(III)?

A

NO2-

50
Q

What is the test for ammonium ions? Explain how it works

A

Add NaOH and heat. Ammonium ions will react with the OH- ions and release ammonia gas, which can be tested for with damp red litmus paper

51
Q

What is the name of a NO3- ion?

A

Nitrate(V)

52
Q

Devarda’s alloy ___ the nitrate(V) ions

A

Reduces

A Level Chemistry OCR B (11 decks)

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