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IMAT Chem > Chapter 8: Chemical Kinetics > Flashcards

Chapter 8: Chemical Kinetics Flashcards

1
Q

What is reaction kinetics?

A

The study of the rates of chemical reactions.

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2
Q

What does the rate of a reaction measure?

A

How quickly the concentration of a reactant or product changes with time.

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3
Q

What does collision theory state about chemical reactions?

A

Particles must collide in the correct orientation and with sufficient energy to react.

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4
Q

What determines the average kinetic energy of particles?

A

The absolute temperature in Kelvin.

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5
Q

How does increasing temperature affect reaction rate?

A

It increases particle speed and the proportion of collisions with energy exceeding activation energy.

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6
Q

What is activation energy (Ea)?

A

The minimum energy required for particles to collide successfully.

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7
Q

What happens if particles do not have sufficient activation energy?

A

No reaction occurs.

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8
Q

What is the effect of concentration on reaction rate?

A

Higher concentration leads to more frequent collisions, increasing the reaction rate.

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9
Q

How does particle size affect the rate of reaction?

A

Smaller particles have greater surface area, increasing collision frequency and rate.

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10
Q

How does pressure affect reactions involving gases?

A

Higher pressure increases the rate by effectively increasing gas concentration.

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11
Q

What is the Boltzmann distribution?

A

It shows the distribution of particle energies at a given temperature.

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12
Q

How does the Boltzmann distribution change with temperature?

A

The curve flattens and shifts to the right as temperature increases.

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13
Q

What is a catalyst?

A

A substance that increases reaction rate by lowering activation energy and remains unchanged at the end.

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14
Q

How does a catalyst affect the Boltzmann distribution?

A

It increases the number of particles with energy greater than activation energy without changing the curve’s shape.

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15
Q

What is a homogeneous catalyst?

A

A catalyst in the same phase as the reactants.

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16
Q

What is a heterogeneous catalyst?

A

A catalyst in a different phase than the reactants.

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17
Q

Why does increasing temperature increase reaction rate?

A

Particles move faster, collide more often, and more particles exceed the activation energy.

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18
Q

How does a heterogeneous catalyst work?

A

It provides a surface for reactants to adsorb, increasing the probability of collisions.

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19
Q

What is the effect of enzymes on biochemical reactions?

A

They speed up reactions under mild conditions by lowering activation energy.

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20
Q

Why are enzymes more efficient than inorganic catalysts?

A

They increase reaction rates by factors of 10⁶ to 10¹² and work specifically without byproducts.

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21
Q

What are the optimal conditions for enzyme activity?

A

Around 35°C, pH 7, and atmospheric pressure.

22
Q

How is activation energy visualized in an energy profile diagram?

A

As the peak energy barrier that must be overcome for reactants to form products.

23
Q

How does temperature affect the proportion of successful collisions?

A

Higher temperatures increase the proportion of particles with energy greater than the activation energy.

24
Q

What is the decomposition of hydrogen peroxide an example of?

A

A reaction catalyzed by a heterogeneous catalyst (MnO₂).

25
Q

Why does increasing surface area increase reaction rate?

A

It allows more contact between reactants, increasing collision opportunities.

26
Q

How does increasing pressure affect gaseous reactants?

A

It compresses the gas, increasing concentration and collision frequency.

27
Q

What are the products of the decomposition of hydrogen peroxide?

A

Water and oxygen.

28
Q

How do enzymes regulate reaction rates in living organisms?

A

By adjusting the amount of enzyme according to need.

29
Q

What are proton exchange membranes used for in fuel cells?

A

To facilitate the transfer of protons during reactions.

30
Q

How does collision geometry affect reaction success?

A

Incorrect geometry prevents the formation of products even if particles collide.

31
Q

What is the role of platinum nanoparticles in fuel cells?

A

They act as catalysts to increase the rate of reactions.

32
Q

What is the primary difference between homogeneous and heterogeneous catalysis?

A

The phase of the catalyst relative to the reactants.

33
Q

Why do enzymes not produce byproducts?

A

They are highly specific and catalyze only one type of reaction.

34
Q

What is an energy profile diagram?

A

A graph showing energy changes during a reaction, including activation energy.

35
Q

How do catalysts lower activation energy?

A

By providing an alternative reaction pathway with a lower energy barrier.

36
Q

What happens to the catalyst at the end of a reaction?

A

It remains chemically unchanged.

37
Q

Why are enzymes considered biological catalysts?

A

They are protein molecules that speed up biochemical reactions.

38
Q

How do enzymes enable reactions at low temperatures?

A

By lowering the activation energy needed for reactions to occur.

39
Q

How is reaction rate affected by the frequency of collisions?

A

More frequent collisions increase the reaction rate.

40
Q

What is the role of MnO₂ in hydrogen peroxide decomposition?

A

It acts as a heterogeneous catalyst to speed up the reaction.

41
Q

What is collision theory?

A

A theory stating that particles must collide with correct orientation and sufficient energy to react.

42
Q

What two factors determine a successful collision?

A

Correct geometry and energy greater than activation energy.

43
Q

What increases the frequency of collisions in a reaction?

A

Higher temperature, pressure, or concentration.

44
Q

Why is activation energy important in collision theory?

A

It determines the minimum energy needed for particles to react.

45
Q

How does a catalyst affect collision theory?

A

It lowers the activation energy, increasing the number of successful collisions.

46
Q

What is the main role of enzymes in living organisms?

A

To enable biochemical reactions to occur quickly at mild conditions.

47
Q

How does temperature affect enzyme activity?

A

It increases activity up to an optimal temperature, after which enzymes denature.

48
Q

Why is pH important for enzyme function?

A

Each enzyme has an optimal pH for maximum activity.

49
Q

What happens to enzymes at extreme pH levels?

A

They can lose their structure and become inactive.

50
Q

Why are enzymes specific to one reaction?

A

Their active site is shaped to bind only specific substrates.

IMAT Chem (9 decks)

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