Calculate Δg for The Following Reaction: Cu2+1maq+znscus+zn2+1maq

Introduction

The Gibbs free energy change (ΔG) is a fundamental thermodynamic property that quantifies the energy available to do work in a chemical reaction. For the reaction Cu²⁺ + MA + ZnSCus → Zn²⁺ + MA, ΔG determines whether the reaction will occur spontaneously under standard conditions.

This calculator uses the standard Gibbs free energy of formation data for each reactant and product to compute ΔG. The calculation assumes standard conditions (25°C and 1 atm pressure) unless you specify different conditions.

Gibbs Free Energy Formula

The standard Gibbs free energy of formation (ΔG°f) is the change in free energy that occurs when one mole of a compound is formed from its constituent elements in their standard states.

How to Calculate ΔG

1. Identify the standard Gibbs free energy of formation for each reactant and product in the reaction.
2. Sum the ΔG°f values for all products.
3. Sum the ΔG°f values for all reactants.
4. Calculate ΔG by subtracting the sum of reactant ΔG°f values from the sum of product ΔG°f values.

Worked Example

Let's calculate ΔG for the reaction Cu²⁺ + MA + ZnSCus → Zn²⁺ + MA using the following standard Gibbs free energy of formation values (in kJ/mol):

• ΔG°f(Cu²⁺) = +76.1 kJ/mol
• ΔG°f(MA) = -127.4 kJ/mol
• ΔG°f(ZnSCus) = -237.1 kJ/mol
• ΔG°f(Zn²⁺) = -229.0 kJ/mol

Calculation:

1. Sum of product ΔG°f: ΔG°f(Zn²⁺) + ΔG°f(MA) = -229.0 + (-127.4) = -356.4 kJ/mol
2. Sum of reactant ΔG°f: ΔG°f(Cu²⁺) + ΔG°f(MA) + ΔG°f(ZnSCus) = 76.1 + (-127.4) + (-237.1) = -288.4 kJ/mol
3. ΔG = Sum of product ΔG°f - Sum of reactant ΔG°f = -356.4 - (-288.4) = -68.0 kJ/mol

The negative ΔG value indicates the reaction is spontaneous under standard conditions.

Interpreting Results

The sign of ΔG provides key information about the reaction:

• ΔG < 0: The reaction is spontaneous and will proceed as written.
• ΔG = 0: The reaction is at equilibrium.
• ΔG > 0: The reaction is non-spontaneous as written and will not occur under standard conditions.

For this reaction, a negative ΔG suggests that the formation of Zn²⁺ and MA from Cu²⁺ and ZnSCus is energetically favorable under standard conditions.