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O Level Chemistry & IP Chemistry Notes by 10 Year Series Author – Chemistry Specialist

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O Level Chemistry – Rate of Reaction Mini Series Part 3

In the last blogpost, we have discussed on the 5 FACTORS that will determine and affect the Rate of Reactions.

Today we shall discuss on the last factor – Effect of Catalysts on Rate of Reaction

Definition:
A catalyst is a substance that speeds up a reaction and remains chemically unchanged at the end of the reaction.

A catalyst works by allowing the reaction to proceed by an alternative pathway that involves a lower activation energy.

Characteristics of a Catalyst:

1. Only a small amount is needed to speed up a chemical reaction

2. It lowers the activation energy of a reaction
3. It is not used up during the reaction. Same amount of catalyst is present at beginning & at the end of reaction

4. It is selective in action. One catalyst cannot act on or speed up all types of reactions. Different catalysts speed up different reactions

5. The physical appearance of catalyst may change at the end of reaction, but it?s chemical properties remain unchanged

6. A catalyst increases the speed, and NOT the yield of a chemical reaction, i.e. the same amount of products is formed whether a catalysts is used of not

7. Impurities can prevent catalysts from working, i.e. catalysts is poisoned or inactivated

In O Level Chemistry Exams, there has been a recent trends that more questions are associated with Catalysts and how it affects the Rate of Reaction.

Let’s check out an exam-based question to see how much you understand:

Question 1:
What statement about catalysis is NOT true?
A. They speed up chemical reactions.
B. They are used up in a chemical reactions
C. Different catalysts catalyse different reactions.
D. Many transition metals are good catalysts.

Related Articles:

  • O Level Chemistry – Rate of Reaction Mini Series Part 1
  • O Level Chemistry – Rate of Reaction Mini Series Part 2
  • O Level Chemistry: Energy Changes (Exo/Endo) & Bond Energy
  • O Level Chemistry: Acids,Bases & Salts / Organic Chemistry
  • O Level Chemistry – Strategies to Predict Products of Electrolysis for Aqueuous Solutions

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Reader Interactions

Comments

  1. Sean Chua says

    January 28, 2015 at 2:51 pm

    Well done guys!

    Keep learning Keep Clarifying!

    Sean Chua

  2. hassan says

    October 30, 2014 at 5:46 am

    Well only B is not true

  3. M-Ali Qureshi says

    April 16, 2013 at 5:30 am

    =) B
    chemical properties always remain unchanged,
    and amount of catalyst dosen’t change during reaction or at the end. remains same!! 🙂

  4. wasif raza says

    August 30, 2012 at 1:43 am

    b is the correct answer

  5. sean says

    October 22, 2008 at 11:53 am

    Hi Rija,

    Well Done!

    Keep Up the Good Work!

    Cheers
    Sean =)

  6. rija says

    October 16, 2008 at 10:06 pm

    b.catalysts are not used up in chemical reactions.

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