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

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O-Level Chemistry: Redox Reactions (Reduction & Oxidation) – Hydrogen Atoms

In the previous post, you have learnt that OXIDATION is the gain of ?oxygen atoms and REDUCTION is the loss of oxygen atoms.

Today, we shall discuss them based on the gain or loss of hydrogen atoms.

OXIDATION is also the loss of hydrogen atoms and REDUCTION is also the gain of hydrogen atoms.

E.g. Reaction of hydrogen sulfide and chlorine to form hydrogen chloride and sulfur

H2S(g) + Cl2(g) –> 2HCl(g) + S(s)

In the above chemical reaction, hydrogen sulfide has lost hydrogen, hence it has been OXIDISED.

Chlorine, on the other hand, has gained hydrogen and is therefore REDUCED.

Hydrogen sulfide is considered the REDUCING AGENT as it has caused the the reduction of chlorine.

Chlorine, on the other hand, has caused the oxidation of hydrogen sulfide and is therefore considered to be the OXIDISING AGENT.

In the above chemical reaction, we say it is a?REDOX Reaction since both?OXIDATION and REDUCTION occurs simultaneously.

Note:

An OXIDISING AGENT helps the other substance to get OXIDISED, and itself gets REDUCED.

A REDUCING AGENT helps the other substance to get REDUCED, and itself gets OXIDISED.

Hope you find the above discussion on REDOX Reactions (based on Hydrogen atoms) useful. Feel free to share it with your friends that are taking O-Level Chemistry (or IGCSE, IB and IP Chemistry).

Hmm…before i end this post, how about trying out a question that test you on the above fundamentals?

Quick Check 1:

Copper (II) oxide reacts with hydrogen based on the following equation:

CuO(s) + H2(g) –> Cu(g) + H2O(l)

State the substance that

(i) has been oxidised

(ii) has been reduced

(iii) is the oxidizing agent

(iii) is the reducing agent

Related Articles:

  • O Level Chemistry – Analogy for Oxidising & Reducing Agents
  • O-Level Chemistry: 5 Rules to Assign Oxidation States (Redox Reactions)
  • O Level Chemistry – Definition of Redox
  • O Level Chemistry – Secrets of Redox & Electrolysis Series
  • O Level Chemistry Question: Redox Reaction

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Reader Interactions

Comments

  1. Blessed sibanda says

    November 22, 2012 at 1:11 am

    Redox reactions a quite easy

  2. Yan says

    August 18, 2012 at 11:50 pm

    Hi thank you ! 😀

  3. sean says

    August 17, 2012 at 10:31 am

    Hi Moses,

    There are 4 ways to describe if something has been oxidised or reduced.

    A) Gain/Loss of Oxygen Atoms
    B) Gain/Loss of Hydrogen Atoms
    C) Gain/Loss of Electrons
    D) Increase/Decrease of Oxidation States (or Oxidation Numbers)

    Now, for a chemical reaction to be a Redox Reaction, you must have both Oxidation Reaction & Reduction Reaction occurring simultaneously.

    Hope the above information helps.

    Cheers!
    Sean Chua

  4. sean says

    August 17, 2012 at 10:19 am

    Hi Yan,

    You must first study the concepts related in Organic Chemistry. The covalent compound CH3COOH that you have indicated is a Carboxylic Acid, which is a covalent compound. For Carboxylic Acid, they will always have a functional group -COOH and you should learn how to draw the full structural formula for it.

    For other carboxylic acids, the structure will be similar to CH3COOH. e.g. C2H5COOH, C3H7COOH, etc.

    Hope the information helps.
    Sean Chua

  5. Kamilu abdullahi says

    August 3, 2012 at 10:59 pm

    Wao this is wonderful! Nw i can cover up with my weak chemistry score

  6. Amy says

    July 12, 2012 at 3:32 am

    Could you please tell me where I can find the answer key for Marshall Cavendish GCE ?O? Level ?Chemistry Matters? Textbook

  7. ayard says

    June 29, 2012 at 3:04 pm

    yh sean, my examz are cummn up and i really want to make a good effort t pass with good grades….so plz try to help me by posting videos on electrolysis…..
    with all the 4 steps

  8. Ramii says

    June 21, 2012 at 4:57 pm

    Is this answer correct?

    (i)H2
    (ii)Cu^+2
    (iii)Cu^+2
    (iv)H2

  9. Sean Wilkinson says

    May 11, 2012 at 10:07 am

    (i) has been oxidised
    Hydrogen
    (ii) has been reduced
    Copper
    (iii) is the oxidizing agent
    Copper
    (iii) is the reducing agent
    Hydrogen

  10. Yan says

    April 26, 2012 at 9:15 pm

    hey hello ! sorry to cut in just like that. i would like to ask, how do you draw the covalent compound of CH3COOH, in other words, vinegar? :O thanks! i mean, yeah simple diagrams i should be able to draw. But what about complex compound like this? what is the way to go about it? Thank you! (:

  11. Moses says

    March 23, 2012 at 9:49 pm

    Which is the best way of defining Redox reaction?

    In the basis of loss and gain of hydrogen,oxygen or the increase/reduction of oxdation states/number?

    Help me please!

  12. Bobga says

    March 1, 2012 at 3:09 pm

    I luv dis. Its jst wat iv been lookx for.

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