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Chemistry > Reaction Rates And Equilibrium > Flashcards

Reaction Rates And Equilibrium Flashcards

1
Q

How do you calculate rate of reaction?

A

Change in concentration over time

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2
Q

What are the units for rate of reaction?

A

Moldm-3s-1

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3
Q

What changes can be used to calculate rate of reaction?

A

Colour change
Mass lost/ gained
PH change
Volume of gas produced

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4
Q

Describe collision theory

A

Particles must collide with enough energy to break bonds

Particles must collide with correct orientation

To have a successful collision

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5
Q

What factors affect ror?

A 
Temperature
Surface area
Concentration of reactants (liquid) 
Pressure (gas) 
Catalyst
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6
Q

How does temperature affect ror?

A

More frequent collisions do to faster movement

Collide with more energy

More succeful collisions

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7
Q

How does surface area affect ror?

A

More exposed reactant

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8
Q

How does pressure affect ror?

A

More particles per volume

More frequent collisions

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9
Q

How does concentration affect ror?

A

More particles per volume

More frequent collisions

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10
Q

How do catalysts affect ror?

A

Provide alternative reaction pathway with a lower activation energy

More collisions are successful

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11
Q

How to Catalysts catalyse a reaction?

A

Provide surface For reaction to occur on

Form intermediate with reactants

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12
Q

What is a homogeneous Catalyst?

A

Catalyst and reactants in same physical state

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13
Q

How do homogeneous catalysts catalyse a reaction?

A

Form an intermediate and are then regenerated forming products

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14
Q

What is a heterogeneous catalyst?

A

Catalyst and reactants are in different physical states

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15
Q

How do heterogeneous catalysts work?

A

Reactants are adsorbed onto surface of catalyst (weak bond form)

Bonds within reactants weaken and break

New bonds form between reactants

Products are desorbed as weak bonds break

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16
Q

Give examples of heterogeneous catalyst processes

A

Haber process

Hydrogenation of alkenes

17
Q

How to the use of catalysts link to sustainability and economic gain?

A

Less energy needed

Less electricity

Less fossil fuels burned (to heat and produce electricity)

Less pollution

Lower cost

18
Q

What is catalyst poisoning?

A

When impurities bind to catalyst taking up space preventing adsorbtion of reactants

19
Q

Give examples of catalyst poisoners

A

Impurities such as sulphur and lead

20
Q

Describe key points of boltzman distribution curve

A

No molecules have no energy

No maximum energy

Area=total number of molecules

X-axis= energy

Y-axis = number of molecules

21
Q

Describe the effect of a higher temp on boltzman distribution curve

A

Peak shifted down to right

Average energy higher but less molecules have it

22
Q

Describe the effect of a lower temp on boltzman distribution curve

A

Peak shifted up to left

More molecules have lower energy

23
Q

Describe the effect of a catalyst on boltzman distribution curve

A

Lowers activation energy

More molecules have energy > activation energy

24
Q

Describe dynamic equilibrium

A

Rate of forward and reverse reaction are equal

Concentration of reactant and products are constant

Closed system

25
Q

What is le chateliers principle?

A

A system at dynamic equilibrium in a closed system will move its position of equilibrium to counteract and changes to conditions made to it to minimise its affects

26
Q

Describe the effect of temperature on dynamic equilibrium

A

Rate of endothermic direction increases

Take in energy lowers temp

27
Q

Describe the effect of pressure on dynamic equilibrium

A

Position of equilibrium will move to side will less gaseous molecules

28
Q

Describe the effect of a catalyst on dynamic equilibrium

A

No effect

Increases rate of forward and reverse reactions by same amount

Equilibrium reached quicker

29
Q

Why can’t high temperatures and pressures and low temperature be used?

A

High temp = expensive and dangerous

High pressure = dangerous

Low temp= slow ror equilibrium reached slower

30
Q

What is the equilibrium constant?

A

Measure of position of equilibrium (relative proportions of reactants and products

31
Q

How do you calculate Kc?

A

Con reactants

(to power of stoichiometry)

32
Q

What are the units for Kc?

A

Vary for every equation

33
Q

What does Kc of

1

> 1
<1

Mean?

A

1= exactly in middle

> 1= towards products

<1= towards reactants

34
Q

Give examples of homogeneous Catalyst reactions

A

Make esters using sulphuric acid

Ozone depletion with chlorine radicals

Chemistry (28 decks)

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