Match each chemical process on the left with the correct classical or modern redox concept… — JAMB UTME

Match each chemical process on the left with the correct classical or modern redox concept on the right that specifically describes the change taking place.

Removal of oxygen from $\text{ZnO(s)}$ to yield $\text{Zn(s)}$ in the reaction $\text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO}$ Classical reduction concept
Addition of oxygen to carbon to form carbon monoxide in $\text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO}$ Classical oxidation concept
Loss of electrons by sodium atoms to form $\text{Na}^+$ in $2\text{Na} + \text{Cl}_2 \rightarrow 2\text{NaCl}$ Modern electron-transfer oxidation
Decrease in oxidation state of nitrogen from $0$ in $\text{N}_2$ to $-3$ in $\text{NH}_3$ Modern oxidation number reduction

Answer

Removal of oxygen from zinc oxide corresponds to classical reduction; addition of oxygen to carbon corresponds to classical oxidation; loss of electrons by sodium corresponds to modern electron-transfer oxidation; and the decrease in oxidation number of nitrogen corresponds to modern oxidation number reduction.

Each chemical transformation is matched according to whether it describes classical oxygen transfer or modern electron/oxidation state changes. Removal of oxygen represents classical reduction; addition of oxygen represents classical oxidation; loss of electrons represents modern electronic oxidation; and a decrease in oxidation number represents modern reduction.

Step-by-Step Solution

Analyze classical definitions of redox

Classical oxidation involves the addition of oxygen or removal of hydrogen, while classical reduction involves the removal of oxygen or addition of hydrogen.

This establishes the ground rules for the first two pairs.

Analyze modern electronic and oxidation number definitions

Modern oxidation is the loss of electrons (OIL) or an increase in oxidation state. Modern reduction is the gain of electrons (RIG) or a decrease in oxidation state.

This establishes the ground rules for the remaining two pairs.

Match each process to its corresponding definition

Zinc oxide losing oxygen is classical reduction. Carbon gaining oxygen is classical oxidation. Sodium losing electrons is modern electronic oxidation. Nitrogen decreasing in oxidation number from 0 to -3 is modern oxidation number reduction.

Applying the concepts directly aligns each process with its primary redox definition.

Key Concept

Classical vs Modern Concepts of Redox Reactions

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