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Calculate Δso for The Following Reaction. N2g + 3f2g 2nf3g

Reviewed by Calculator Editorial Team

This calculator helps you determine the standard free energy change (ΔG°) for the reaction N2(g) + 3F2(g) → 2NF3(g) using thermochemical data. The standard free energy change is a key thermodynamic property that indicates the spontaneity of a reaction under standard conditions.

Introduction

The standard free energy change (ΔG°) is a fundamental thermodynamic property that describes the energy available to do work in a chemical reaction under standard conditions (25°C and 1 atm pressure). For the reaction N2(g) + 3F2(g) → 2NF3(g), ΔG° can be calculated using the standard Gibbs free energies of formation (ΔG°f) of the reactants and products.

Understanding ΔG° is crucial in chemistry as it helps predict whether a reaction will occur spontaneously (ΔG° < 0), is at equilibrium (ΔG° = 0), or is non-spontaneous (ΔG° > 0). This calculator provides a straightforward way to compute ΔG° for the given reaction using standard thermochemical data.

Formula

The standard free energy change for a reaction can be calculated using the following formula:

ΔG°reaction = ΣΔG°f(products) - ΣΔG°f(reactants)

Where:

  • ΔG°f(products) is the sum of the standard Gibbs free energies of formation of the products
  • ΔG°f(reactants) is the sum of the standard Gibbs free energies of formation of the reactants

For the reaction N2(g) + 3F2(g) → 2NF3(g), the formula becomes:

ΔG°reaction = [2 × ΔG°f(NF3(g))] - [ΔG°f(N2(g)) + 3 × ΔG°f(F2(g))]

Calculation

To calculate ΔG° for the reaction, you need the standard Gibbs free energies of formation for nitrogen gas (N2(g)), fluorine gas (F2(g)), and nitrogen trifluoride gas (NF3(g)). These values are typically available in standard thermochemical tables.

Using the standard Gibbs free energies of formation:

  • ΔG°f(N2(g)) = 0 kJ/mol
  • ΔG°f(F2(g)) = 0 kJ/mol
  • ΔG°f(NF3(g)) = -266.6 kJ/mol

The calculation proceeds as follows:

ΔG°reaction = [2 × (-266.6 kJ/mol)] - [0 kJ/mol + 3 × 0 kJ/mol] = -533.2 kJ/mol

This result indicates that the reaction is highly spontaneous under standard conditions.

Example

Let's consider an example where we calculate ΔG° for the reaction N2(g) + 3F2(g) → 2NF3(g) using the standard Gibbs free energies of formation provided in the calculation section.

Given:

  • ΔG°f(N2(g)) = 0 kJ/mol
  • ΔG°f(F2(g)) = 0 kJ/mol
  • ΔG°f(NF3(g)) = -266.6 kJ/mol

The calculation is as follows:

ΔG°reaction = [2 × (-266.6 kJ/mol)] - [0 kJ/mol + 3 × 0 kJ/mol] = -533.2 kJ/mol

The negative value of ΔG° indicates that the reaction is spontaneous under standard conditions, releasing 533.2 kJ of free energy per mole of reaction.

FAQ

What is the standard free energy change (ΔG°)?

The standard free energy change (ΔG°) is a thermodynamic property that measures the energy available to do work in a chemical reaction under standard conditions (25°C and 1 atm pressure). It indicates the spontaneity of a reaction.

How is ΔG° calculated for a reaction?

ΔG° for a reaction is calculated using the standard Gibbs free energies of formation of the reactants and products. The formula is ΔG°reaction = ΣΔG°f(products) - ΣΔG°f(reactants).

What does a negative ΔG° indicate?

A negative ΔG° indicates that the reaction is spontaneous under standard conditions, meaning it will proceed in the forward direction without additional energy input.

Where can I find standard Gibbs free energies of formation?

Standard Gibbs free energies of formation can be found in standard thermochemical tables, such as those published by the National Institute of Standards and Technology (NIST) or other authoritative sources in physical chemistry.