1. What is Standard Enthalpy of Reaction given Gibbs Free Energy?

Definition: This calculator determines the change in enthalpy (ΔH) of a reaction using Gibbs free energy (G), temperature (T), and change in entropy (ΔS).

Purpose: It helps chemists and engineers understand the heat content changes in chemical reactions at constant temperature and pressure.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \Delta H \) — Change in enthalpy (J/kg)
• \( G \) — Gibbs free energy (J)
• \( T \) — Temperature (K)
• \( \Delta S \) — Change in entropy (J/(kg·K))

Explanation: The formula relates the thermodynamic potentials and shows how enthalpy change depends on both energy and disorder changes.

3. Importance of Enthalpy Calculation

Details: Knowing ΔH helps predict whether reactions will be exothermic (release heat) or endothermic (absorb heat), crucial for process design and safety.

4. Using the Calculator

Tips: Enter Gibbs free energy in joules, temperature in kelvin, and entropy change in J/(kg·K). Temperature must be > 0K.

5. Frequently Asked Questions (FAQ)

Q1: What are typical units for these values?
A: Gibbs energy in joules (J), temperature in kelvin (K), entropy in J/(kg·K), and enthalpy in J/kg.

Q2: Can I use Celsius for temperature?
A: No, you must convert to Kelvin first (K = °C + 273.15).

Q3: What's the significance of negative ΔH?
A: Negative ΔH indicates an exothermic reaction (heat released), positive means endothermic (heat absorbed).

Q4: How accurate is this calculation?
A: It's theoretically exact for standard conditions. Real-world accuracy depends on input data quality.

Q5: Where can I find Gibbs free energy values?
A: Thermodynamic tables or databases provide standard Gibbs free energies of formation for many compounds.