Chapter: Chemical Reactions and Equations
Which one of the following is not an example ofa redox reaction?
Redox reactions involve the transfer of electrons, leading to changes in oxidation states of reactants. The general equation governing redox reactions can be represented as:
Oxidation: \( \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \)
Reduction: \( \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \)
The evaluation of each option determines if they are redox reactions:
No change in oxidation states:
Oxidation State of Al: +3 (both sides)
Oxidation State of Cl: -1 (both sides)
Redox Reaction:
Oxidation: \( \text{Na}^{+} \rightarrow \text{Na}^0 \)
Reduction: \( \text{H}^0 \rightarrow \text{H}_2 \)
Redox Reaction:
Oxidation: \( \text{Fe}^0 \rightarrow \text{Fe}^{+3} \)
Reduction: \( \text{O}_2^{0} \rightarrow \text{O}^{-2} \)
Redox Reaction:
Oxidation: \( \text{Zn}^0 \rightarrow \text{Zn}^{+2} \)
Reduction: \( \text{Cu}^{+2} \rightarrow \text{Cu}^0 \)
Options B, C, and D are valid redox reactions as they involve changes in oxidation states, while Option A is an acid-base reaction (no change in oxidation states).
Mnemonic: "LEO says GER" — Lose Electrons Oxidation, Gain Electrons Reduction.
A comparison table showing each reaction and pointing out oxidation states for reactants and products would clarify the nature of redox reactions.
Verified against NCERT Class 11 Chemistry, Chapter 8 (Redox Reactions).
Which one of the following statements is NOT correct for the given reaction?
Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)
The reaction follows the principles of the reactivity series of metals. Iron displaces copper from copper sulfate solution, indicating that iron is more reactive.
In the reaction:
Here, iron (Fe) oxidizes to Fe²⁺ and reduces Cu²⁺ to Cu. Thus:
Remember, "Higher on the list, easier to displace" for reactivity series of metals.
Verified against NCERT Class XII Chemistry Chapter 7 (Redox Reactions).
Hydrogenation of vegetable oils using nickel catalyst is an example of
Consider a diagram showing the structure of vegetable oils (unsaturated) transitioning into vegetable ghee (saturated) through the process of hydrogenation, highlighting the breaking of double bonds.
Verified against NCERT Class XI Chemistry, Chapter on Organic Chemistry: Hydrocarbons.
In the following redox reaction, which compound is acting as a reducing agent?
N2H4 + 2H2O2 → N2 + 4H2O
The reaction follows the principles of redox chemistry, where reducing and oxidizing agents are defined based on electron transfer. Here, N2H4 (hydrazine) undergoes oxidation while H2O2 (hydrogen peroxide) serves as the oxidizing agent.
The given reaction:
Analyzing oxidation states:
Change in oxidation states signifies:
Conclusion: N2H4 is acting as the reducing agent.
Remember: "OIL RIG" - Oxidation Is Loss, Reduction Is Gain. N2H4 loses electrons, hence it is oxidized.
A flowchart illustrating the electron transfer and changes in oxidation states during the reaction between N2H4 and H2O2 would clarify the redox processes involved, highlighting the roles of reducing and oxidizing agents.
Verified against NCERT Class XII Chemistry, Chapter on Redox Reactions.
Which one of the following statements regarding oxidation and reduction reaction is NOT correct?
Option A is correct. The incorrect statement is that losing hydrogen refers to oxidation, not reduction.
The processes of oxidation and reduction involve changes in the gain or loss of elements like oxygen or hydrogen, or electrons. This question tests the conceptual understanding of how these reactions affect compounds.
Use 'OIL RIG' as a mnemonic: "Oxidation Is Loss, Reduction Is Gain" of electrons.
Oxidation and reduction definitions: oxidation is loss of electrons/hydrogen or gain of oxygen; reduction is gain of electrons/hydrogen or loss of oxygen.
A diagram illustrating a molecule, highlighting changes when it undergoes oxidation with oxygen atoms being attached, and reduction with hydrogen atoms being added or oxygen atoms being removed.
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