The position of some metals in the electrochemical series in decreasing electropositive character is — Electrochemistry Chemistry Question

💡 Solution & Explanation

Step 1 - Understanding Electropositive Character and Reactivity Electropositive character refers to the tendency of a metal to lose electrons and form positive ions. The given decreasing order of electropositive character is: $$\ce{Mg > Al > Zn > Cu > Ag}$$ This means aluminium ($\ce{Al}$) is significantly more electropositive and reactive than copper ($\ce{Cu}$). Step 2 - Analyzing the Feasibility of the Chemical Reaction When a copper spoon ($\ce{Cu}$) is used to stir a solution of aluminium nitrate ($\ce{Al(NO3)3}$), the hypothetical displacement reaction would be: $$\ce{3 Cu(s) + 2 Al^3+(aq) -> 3 Cu^2+(aq) + 2 Al(s)}$$ The standard cell potential: $$E^\circ_{\text{cell}} = E^\circ(\ce{Al^3+|Al}) - E^\circ(\ce{Cu^2+|Cu}) = -1.66\text{ V} - 0.34\text{ V} = -2.00\text{ V}$$ Since $E^\circ_{\text{cell}} < 0$, the reaction is thermodynamically non-spontaneous ($\Delta G^\circ > 0$). Step 3 - Evaluation of the Options * **Option (A) is incorrect:** The spoon cannot coat with aluminium because copper cannot reduce $\ce{Al^3+}$. * **Option (B) is incorrect:** Alloy formation requires melting at high temperatures, not stirring an aqueous solution. * **Option (C) is incorrect:** The solution becomes blue only if copper dissolves to give $\ce{Cu^2+}$, which is non-spontaneous here. * **Option (D) is correct:** Since copper is less electropositive than aluminium, no chemical change will take place. $$\text{Correct Option: } \boxed{\text{D}}$$