Question

Mg (s) + Br₂ (I) → Mg²⁺ (aq) + 2Br⁻ (aq)
Formulate a cell for given reaction.

Answer 1

Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)

For Magnesium  

Mg(s) → Mg2+(aq)

Enthalpy of Atomization: Mg(s) → Mg(g)       ΔHa = +146 kJ mol−1

1st and 2nd Ionization Energy: Mg(g) → Mg2+(g) + 2e−        ΔHi = +2187 kJ mol−1

Enthalpy of Hydration: Mg2+(g) → Mg2+(aq)      ΔHh = -1926 kJ mol−1

Total Enthalpy Change:

ΔHMg = +146 + 2187 - 1926 = +407 kJ mol−1

For Copper

Cu2+(aq) → Cu(s)

Enthalpy of Atomization: Cu(s) → Cu(g)       ΔHa = +338 kJ mol−1

1st and 2nd Ionization Energy: Cu(g) → Cu2+(g) + 2e−       ΔHi = +2703 kJ mol−1

Enthalpy of Hydration: Cu2+(g) → Cu2+(aq)       ΔHh = -2161 kJ mol−1