Question

A. Use the following steps to balance the redox reaction below. Al(s) Ni2 (aq) Ni(s) Al3 (aq)

i. Write the oxidation and reduction half-reactions. Make sure each half-reaction is balanced for number of atoms and charge.
ii. Multiply each half-reaction by the correct number in order to balance charges for the two half-reactions.
iii. Add the equations and simplify to get a balanced equation.

Answer 1

2Al(s) +3Ni²⁺(aq) ⟶ 2Al³⁺(aq) + 3Ni(s)

Step-by-step explanation:

The unbalanced equation is

Al(s) + Ni²⁺(aq) ⟶ Ni(s) + Al³⁺(aq)

(i) Half-reactions

Al(s) ⟶ Al³⁺(aq) + 3e⁻

Ni²⁺(aq) + 2e⁻ ⟶ Ni(s)

(ii) Balance charges

2 × [Al(s) ⟶ Al³⁺(aq) + 3e⁻]

3 × [Ni²⁺(aq) + 2e⁻ ⟶ Ni(s)]

gives

2Al(s) ⟶ 2Al³⁺(aq) + 6e⁻

3Ni²⁺(aq) + 6e⁻ ⟶ 3Ni(s)

(iii) Add equations

2Al(s) ⟶ 2Al³⁺(aq) + 6e⁻

3Ni²⁺(aq) + 6e⁻ ⟶ 3Ni(s)

2Al(s) +3Ni²⁺(aq) + 6e⁻ ⟶ 2Al³⁺(aq) + 3Ni(s) + 6e⁻

Simplify (cancel electrons)

2Al(s) +3Ni²⁺(aq) ⟶ 2Al³⁺(aq) + 3Ni(s)