Mechanisms of Catalysis - The Intermediate Formation Theory Flashcards

1
Q

Who suggested this theory?

A

Arrhenius

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2
Q

What did Arrhenius suggest in relation to the mechanisms of catalysis?

A

He suggested that a catalyst works by forming an intermediate compound
i.e. One or multiple reactants combine with the catalyst to form an intermediate compound that may only exist for a very short time and may be difficult to detect

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3
Q

Give an example of a reaction which suggests Arrhenius’ Intermediate Formation Theory

A

The oxidation of potassium sodium tartrate using hydrogen peroxide which is catalysed by Co2+ ions

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4
Q

How does the oxidation of potassium sodium tartrate using hydrogen peroxide suggest Arrhenius’ theory is correct?
(3 Key steps)

A
  1. The solution of potassium sodium tartrate and crystals of pink cobalt (II) chloride is pink at first
  2. When some 100- volume hydrogen peroxide is added fizzing is observed and the solution becomes green
  3. After a few seconds the solution ceases to fizz and the solution becomes pink again
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5
Q

What does the colour change from pink to green indicate?

A

That a new substance has been formed

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6
Q

What does the change of the green colour back to pink suggest?

A

That the new substance is an intermediate

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7
Q

What does the fizzing of the solution suggest?

A

That the intermediate is reacting

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8
Q

What does the restoration of the pink colour suggest?

A

That the Co2+ ions have not been used up

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9
Q

What suggests that a new substance has been formed?

A

The colour change from pink to green

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10
Q

What suggests that the new substance is an intermediate?

A

The change of the green colour back to pink

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11
Q

What suggests that the intermediate is reacting?

A

The fizzing of the green solution

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12
Q

What suggests that the Co2+ ions have not been used up?

A

The restoration of the pink colour

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13
Q

What is the source of the catalyst in this experiment?

A

Crystals of pink cobalt (II) chloride

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14
Q

What is the first step to this experiment?

A

Dissolving the potassium sodium tartrate in hot water with some crystals of pink cobalt (II) chloride

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