Disproportionation Reactions for NEET: Key Points, Tricks & MCQs
Disproportionation ReactionsRedox ReactionsNEET ChemistryNEET 2025Oxidation StateTypes of Redox
Disproportionation Reactions for NEET: Key Points, Tricks & MCQs
Redox Reactions·2 min read·NEET 2026
What NEET Asks
Identification: Recognize reactions where a single element undergoes both oxidation and reduction.
Oxidation State Calculation: Crucial for determining if an element can disproportionate.
Examples: Be familiar with common examples like H₂O₂, Cl₂, P₄, S in specific mediums.
Key Points
A disproportionation reaction is a type of redox reaction.
The same element in a single reactant is simultaneously oxidized and reduced.
The element must exist in an intermediate oxidation state to disproportionate.
It must be able to achieve both higher and lower oxidation states from its initial state.
Elements in their highest or lowest possible oxidation state cannot disproportionate.
Examples include H₂O₂ (oxygen), Cl₂ (chlorine) in alkaline solutions, P₄ (phosphorus) in alkali.
Must-Know Formula / Reaction
2H₂O₂(aq) → 2H₂O(l) + O₂(g)
Here, Oxygen in H₂O₂ has an oxidation state of -1.
In H₂O, Oxygen is -2 (reduced).
In O₂, Oxygen is 0 (oxidized).
Common Mistakes
Students often confuse disproportionation with intermolecular redox reactions where different elements change oxidation states.
Don't forget to check the oxidation state of the same element in all products.
Overlooking the reaction conditions (acidic vs. basic medium) which can dictate whether disproportionation occurs and what products are formed.
Rapid Revision
Disproportionation: one element, one reactant, simultaneously oxidized and reduced. Requires intermediate oxidation state. Look for elements like O in H₂O₂, Cl in Cl₂ (base), P₄ (base), S (base). Cannot happen if element is in max/min O.S.
Frequently Asked Questions
What is a disproportionation reaction in simple terms?▾
A disproportionation reaction is a special type of redox reaction where a single element in one reactant simultaneously undergoes both oxidation (loss of electrons) and reduction (gain of electrons). This means the element's oxidation state increases in one product and decreases in another.
How can I identify if a given reaction is a disproportionation reaction?▾
To identify a disproportionation reaction, first calculate the oxidation state of the key element in the reactant. Then, check its oxidation states in all the products. If the same element has a higher oxidation state in one product and a lower one in another, then it's a disproportionation reaction.
Which elements or compounds typically undergo disproportionation?▾
Elements or compounds where the key element is in an intermediate oxidation state are capable of disproportionation. Common examples include hydrogen peroxide (oxygen is -1), halogens like chlorine or bromine in alkaline solutions (halogen is 0), and phosphorus or sulfur in basic solutions.
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