Question detail
Calculate the Gibbs free energy change (ΔG) for a reaction where the enthalpy change (ΔH) is -150 kJ and the entropy change (ΔS) is 200 J/K at a temperature of 298 K (A-level cue 4706b9fd focus)
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Thermodynamics (A-level only)
Question
Calculate the Gibbs free energy change (ΔG) for a reaction where the enthalpy change (ΔH) is -150 kJ and the entropy change (ΔS) is 200 J/K at a temperature of 298 K (A-level cue 4706b9fd focus)
Answer
-150 kJ. This answer is anchored to Entropy and Gibbs free energy (A-level only). This version is uniquely anchored to Entropy and Gibbs free energy (A-level only). Retrieval anchor: A-level cue 4706b9fd.
Explanation
-150 kJ. This answer is anchored to Entropy and Gibbs free energy (A-level only). is correct because it supports the objective: Use ΔG = ΔH - TΔS to calculate Gibbs free energy change.. The reasoning stays within Entropy and Gibbs free energy (A-level only) and avoids drifting into a similar A-Level Chemistry idea. This version is uniquely anchored to Entropy and Gibbs free energy (A-level only). Retrieval anchor: A-level cue 4706b9fd. This item is treated as conceptual revision rather than a formal calculation item because the validated answer is an explanation or option choice, not a worked numerical response.
Common mistake
Incorrect Use of Temperature Units
Students often forget to convert temperature from Celsius to Kelvin when using the Gibbs free energy equation ΔG = ΔH - TΔS.
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.
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