Question

Does a reaction occur when an aqueous solution of nicl2(aq) is added to a test tube containing strips of metallic zinc?

Answer 1

Answer is: yes, reaction occurs.

Reactivity series is an empirical progression of a series of metals, arranged by their reactivity from highest to lowest (alkaline metals have highest reactivity and Noble metals lowest reactivity).

Metal higher in the reactivity series will displace another, zinc is more reactive than nickel.

Chemical reaction: Zn(s) + NiCl₂(aq) → ZnCl₂(aq) + Ni(s).

Ionic reaction: Zn(s) + Ni²⁺(aq) + 2Cl⁻(aq) → Zn²⁺(aq) + 2Cl⁻(aq) + Ni(s).

Net ionic reaction: Zn(s) + Ni²⁺(aq) → Zn²⁺(aq) + Ni(s).

Zinc metal is oxidized (from oxidation number 0 to +2) and nickel is reduced (from oxidation number +2 to 0).

Answer 2

To know if a reaction would occur, we refer to the reactivity series. Looking at the reactivity series, the zinc is at the upper list than nickel, therefore we could say that a reaction would occur. This would actually be a replacement reaction:

NiCl2 + Zn --> ZnCl2 + Ni