Use ΔG = ΔH - TΔS to calculate Gibbs free energy change.

In the subtopic Entropy and Gibbs free energy (A-level only), this AQA A-Level Chemistry 7405 learning objective focuses on use ΔG = ΔH - TΔS to calculate Gibbs free energy change. It belongs to Thermodynamics (A-level only), so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include Gibbs free energy. Feasibility of a reaction. means a reaction is considered feasible if the Gibbs free energy change (ΔG) is negative, indicating that the reaction can occur spontaneously under the given conditions Avoid the mistake of students often forget to convert temperature from Celsius to Kelvin when using the Gibbs free energy equation ΔG = ΔH - TΔS; instead, always convert the temperature to Kelvin by adding 273.15 to the Celsius value before substituting into the equation. For example, if the temperature is 25°C, convert it to Kelvin: T = 25 + 273.15 = 298.15 K. Then, use this value in the Gibbs free energy calculation For exam answers, use the formula ΔG = ΔH - TΔS to find the Gibbs free energy change for a reaction