Calculate Δgrxn at 298 K for The Following Reaction: I2g+br2g2ibrgkp436

Introduction

The standard Gibbs free energy change (ΔG°rxn) is a fundamental thermodynamic property that indicates the spontaneity of a chemical reaction under standard conditions. For the reaction I2(g) + Br2(g) → 2IBr(g), we can calculate ΔG°rxn using the standard Gibbs free energies of formation (ΔG°f) for each compound involved.

This calculation assumes standard conditions of 298 K and 1 atm pressure, and that all reactants and products are in their standard states.

Formula

The standard Gibbs free energy change for a reaction is calculated using the following formula:

Where:

• ΔG°rxn is the standard Gibbs free energy change for the reaction
• ΔG°f(products) is the sum of the standard Gibbs free energies of formation for all products
• ΔG°f(reactants) is the sum of the standard Gibbs free energies of formation for all reactants

Calculation

To calculate ΔG°rxn for the reaction I2(g) + Br2(g) → 2IBr(g), we need the standard Gibbs free energies of formation for iodine (I2), bromine (Br2), and iodine bromide (IBr).

Using standard thermodynamic data:

• ΔG°f(I2) = -60.7 kJ/mol
• ΔG°f(Br2) = -30.6 kJ/mol
• ΔG°f(IBr) = -32.5 kJ/mol

The calculation proceeds as follows:

The negative sign indicates that the reaction is spontaneous under standard conditions.

Interpretation

The calculated ΔG°rxn of 26.3 kJ/mol for the reaction I2(g) + Br2(g) → 2IBr(g) indicates that the reaction is spontaneous under standard conditions. This means that the reaction will proceed in the forward direction, forming iodine bromide, without the need for an external energy input.

The positive value of ΔG°rxn suggests that the reaction is favorable and will occur naturally. However, the relatively small magnitude of ΔG°rxn indicates that the reaction may not proceed rapidly or may require activation energy to overcome kinetic barriers.