Match each chemical system in Column A with its correct outcome and rationale based on the… — JAMB UTME

Match each chemical system in Column A with its correct outcome and rationale based on the electrochemical series in Column B.

Potassium metal ( $\text{K}$ ) added to aqueous zinc sulfate solution ( $\text{ZnSO}_4$ )Spontaneous displacement occurs because the metal has a more negative standard reduction potential than the metal ion in solution.
Copper metal ( $\text{Cu}$ ) added to dilute hydrochloric acid ( $\text{HCl}$ )No reaction occurs because the metal has a positive reduction potential relative to hydrogen.
Fluorine gas ( $\text{F}_2$ ) bubbled through aqueous sodium chloride solution ( $\text{NaCl}$ )Spontaneous oxidation of halide ions occurs because the halogen has a higher standard reduction potential.
Silver metal ( $\text{Ag}$ ) added to gold(III) nitrate solution ( $\text{Au(NO}_3)_3$ )Spontaneous displacement occurs because the uncombined metal acts as a stronger reducing agent than the noble metal being displaced.

Answer

Potassium with zinc sulfate matches spontaneous displacement due to a more negative reduction potential; Copper with hydrochloric acid matches no reaction due to a positive reduction potential relative to hydrogen; Fluorine with sodium chloride matches spontaneous halide oxidation due to a higher reduction potential; Silver with gold(III) nitrate matches spontaneous metal displacement because silver acts as a stronger reducing agent than gold.

Each chemical system correctly pairs with its electrochemical behavior: Potassium displaces Zinc because it possesses a more negative reduction potential; Copper does not react with dilute acid because its reduction potential is positive relative to hydrogen; Fluorine displaces chloride ions because it has a higher reduction potential and thus greater oxidizing power; Silver displaces gold ions because silver has a lower reduction potential than gold, making it the stronger reducing agent.

Step-by-Step Solution

Analyze position of Potassium and Zinc in the electrochemical series.

Potassium (

E^\circ = -2.93\text{ V}

) has a more negative reduction potential than Zinc (

E^\circ = -0.76\text{ V}

), making it a stronger reducing agent.

Metals with more negative standard reduction potentials spontaneously displace ions of metals below them in the series.

Evaluate the reactivity of Copper in non-oxidizing acid.

Copper (

E^\circ = +0.34\text{ V}

) lies below Hydrogen (

E^\circ = 0.00\text{ V}

) in the electrochemical series.

Metals with positive reduction potentials cannot spontaneously reduce hydrogen ions to evolve

\text{H}_2

gas.

Compare oxidizing strengths of Fluorine and Chlorine.

Fluorine (

E^\circ = +2.87\text{ V}

) has a higher reduction potential than Chlorine (

E^\circ = +1.36\text{ V}

A halogen with a higher reduction potential acts as a stronger oxidizing agent and displaces halide ions with lower reduction potentials.

Determine feasibility of displacement between Silver and Gold ions.

Silver (

E^\circ = +0.80\text{ V}

) is more easily oxidized than Gold (

E^\circ = +1.50\text{ V}

The metal with the smaller reduction potential acts as the reducing agent, resulting in a positive standard cell potential (

E^\circ_{\text{cell}} > 0

Key Concept

Electrochemical Series and Reaction Spontaneity

Estimated Time:1m 30s

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