Redox+Reaction

- ** "Redox" ** comes from the words “**red**uction” and “**ox**idation” - Happens in everyday life, namely chemical reactions such as rusting, burning , respiration and photosynthesis

- “Oxidation” refers to the gain of oxygen;

- “Reduction” refers to the loss of oxygen

-"Redox" = “Oxidation” and “Reduction” goes on side-by-side

An example of “Oxidation” and “Reduction” going on side-by-side


 * A Comic Representation**


 * Example 2**

Zinc reacts with copper (II) oxide.


 * Zn (s) + CuO (s) --> ZnO (s) + Cu (s)**

In the reaction, copper (II) oxide loses oxygen. Thus, it is reduced. Zinc, on the other hand, gains oxygen. Thus, it is oxidised.


 * Test for reducing agents**

Using aqueous potassium manganate (VII); KMnO4 needs to be acidified. Purple MnO4- permanganate ion will turn into colourless Mn2+ manganese ion
 * 1) 1cm3 of potassium manganate (VII) solution is poured into a test tube, followed by 1cm3of dilute sulfuric acid.
 * 2) A few drops of this acidified potassium manganate is added to the unknown solution.
 * 3) If the purple MnO4- solution turns colourless, then the MnO4- has been reduced to Mn2+
 * 4) This means that the unknown substance caused the reduction and was hence a reducing agent

 //Concentrated and diluted potassium manganate (VII) solution //

Using aqueous potassium dichromate (VI); K2Cr2O7 needs to be acidified. Orange Cr2O72- dichromate ion will turn into green Cr3+ chromium ion in the presence of a reducing agent Same method as above is used.
 * 2) **

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//Acidified potassium dichromate (VI) Reduced potassium dichromate (VI) - Green Cr3+ Chromium ions //

 * Test for oxidising agents**

Using aqueous potassium iodide, KI <span style="font-family: Arial,Helvetica,sans-serif;">Colourless I- iodide ion will turn into brown I2 iodine molecule
 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">A few drops of aqueous potassium iodide is added to the unknown solution.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">If the colourless I- solution turns into brown, then the I- has been oxidized to I2
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">This means that the unknown substance caused the oxidation and was hence a oxidizing agent


 * Test your knowledge**

a. An iron nail is dropped into a solution of copper sulfate. The nail becomes coat with copper metal. What is the reaction that took place. Which was reduced, and which was oxidised?

b. Given the reaction ZnO + X + heat --> Zn + XO Which element, represented by X, is used industrially to reduced the ZnO to Zn? (MCQ)

1. Cu 2. C 3. SN 4. Pb


 * Answer (a)**

Fe + CuSO4 --> FeSO4 + Cu Iron has been oxidised while copper (II) sulfate has been reduced.


 * Answer (b)**

Correct Answer: 2. <span style="background-color: #fffff0; font-family: Arial,Helvetica,sans-serif; text-align: -webkit-left;">Carbon is a readily available reducing agent widely used in industry.It forms four covalent bonds with other carbon atoms as well as many other kinds of atoms. It has an almost limitless ability to bond with other carbon atoms, making possible a very large number of compounds. These compounds are used in many reactions in nature and industry.

**<span style="background-color: #fffff0; font-family: Arial,Helvetica,sans-serif; text-align: -webkit-left;">Further Enrichment - Video **
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**Reference**
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Chemistry Insights, "O" Level 2nd Edition

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