Which of the following reactions would be classed as redox reactions? Explain why this isCorrosion of iron to iron (III) oxide (Fe2O3) and burning of magnesium in air

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swatisakk's profile pic

swatisakk | (Level 1) Adjunct Educator

Posted on

Burning of Magnesium in air is a Redox reaction. Red-ox reaction is a reaction in which one of the elements/compounds loses electrons and the other gains electrons.

In case of Magnesium, it reacts with oxygen to lose 2 electrons to form Mg2+ and Oxygen gains 4 electrons to form 2O2-

The reaction is:

2Mg + O2 -> 2[Mg2+] [O2-]

llltkl's profile pic

llltkl | College Teacher | (Level 3) Valedictorian

Posted on

In fact both of them are examples of redox reactions.

Burning of magnesium: 2Mg + O2 -----> 2MgO

Here, oxidation number of Mg changes from 0 to +2 and that of oxygen changes from 0 to -2. So this is definitely a redox reaction. 

Corrosion of iron to iron (III) oxide:4Fe + 3O2 -----> 2Fe2O3

Here, oxidation number of Fe changes from 0 to +3 and that of oxygen changes from 0 to -2. So this is also a redox reaction. Also please see the comments and other reactions associated with rusting in the given link. 

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