1. Identify the Half-Reactions:
* Oxidation: Mg(s) → Mg²⁺(aq) + 2e⁻
* Reduction: Cu²⁺(aq) + 2e⁻ → Cu(s)
2. Look Up Standard Reduction Potentials:
You'll need to find the standard reduction potentials (E°) for each half-reaction. These values are typically found in tables.
* E°(Mg²⁺/Mg) = -2.37 V
* E°(Cu²⁺/Cu) = +0.34 V
3. Determine the Overall Cell Potential:
The overall cell potential (E°cell) is calculated as:
E°cell = E°(reduction) - E°(oxidation)
* Since the magnesium half-reaction is the oxidation (electrons are being lost), we need to flip the sign of its reduction potential.
E°cell = +0.34 V - (-2.37 V)
E°cell = +2.71 V
Therefore, the overall voltage for the redox reaction is +2.71 V.
Important Notes:
* Spontaneous Reactions: A positive cell potential indicates that the reaction is spontaneous under standard conditions (25°C, 1 atm pressure, 1 M concentration).
* Non-Standard Conditions: If the reaction is not occurring under standard conditions, you would need to use the Nernst equation to calculate the cell potential.
