Calculadora de Energia de Gibbs

The Gibbs Energy Calculator determines the spontaneity of a chemical reaction from the change in enthalpy (ΔH), temperature (T), and change in entropy (ΔS). The Gibbs free energy (ΔG) is calculated using the formula ΔG = ΔH − T·ΔS, where ΔH and ΔS are provided by the user. The result indicates whether the reaction is spontaneous (ΔG < 0), non-spontaneous (ΔG > 0), or at equilibrium (ΔG = 0). The calculator automatically converts ΔS from J/K to kJ/K to ensure unit consistency.

This tool is useful for students and professionals in chemistry who need to predict the feasibility of reactions at different temperatures. For example, when analyzing the decomposition of calcium carbonate, one can check at which temperature the reaction becomes spontaneous. The calculator also aids in planning industrial processes, such as ammonia synthesis, where temperature control is crucial to optimize yield.

When using the calculator, it is important to enter ΔH and ΔS with the correct signs (positive or negative) and the temperature in Kelvin. Typical ΔH values range from tens to hundreds of kJ/mol, while ΔS usually ranges from tens to hundreds of J/(mol·K). The calculator assumes that the provided values are constant over the temperature range considered, which is a valid approximation for many practical cases.

Precautions: do not confuse J with kJ for ΔS; the calculator performs the conversion automatically. Additionally, the spontaneity predicted by ΔG does not inform about the reaction rate. Reactions with negative ΔG can be very slow if the activation energy is high. Finally, the equation ΔG = ΔH − T·ΔS is valid only for processes at constant pressure, which is the most common laboratory condition.