AP Chemistry · Unit 9: Thermodynamics and Electrochemistry
9.6 Free Energy of Dissolution
In short
You are expected to understand that the free energy change (ΔG°) for the dissolution of a substance reflects three main factors: the breaking of intermolecular interactions that hold the solid together, the reorganization of the solvent around the dissolved species, and the interaction of the dissolved species with the solvent.
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What else do you need to know about Free Energy of Dissolution?
You must be able to estimate the sign and relative magnitude of the enthalpic and entropic contributions to each of these factors. However, the specification explicitly notes that making predictions for the total change in free energy of dissolution can be challenging due to cancellations among the free energies associated with these three factors; therefore, predicting the overall total change is not expected.
How is Free Energy of Dissolution tested on the exam?
You may be assessed on your ability to explain the relationship between salt solubility and changes in enthalpy and entropy. This topic is paired with the science practice of Model Analysis (Skill 4.D), meaning you should be prepared to explain the degree to which a given model or representation describes the connection between particulate-level properties (such as intermolecular interactions and solvent reorganization) and macroscopic properties (such as solubility).
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Free Energy of Dissolution: common questions
What do you need to know about Free Energy of Dissolution for AP Chemistry?
You are expected to understand that the free energy change (ΔG°) for the dissolution of a substance reflects three main factors: the breaking of intermolecular interactions that hold the solid together, the reorganization of the solvent around the dissolved species, and the interaction of the dissolved species with the solvent.
How is Free Energy of Dissolution tested on the AP Chemistry exam?
You may be assessed on your ability to explain the relationship between salt solubility and changes in enthalpy and entropy.
Where does Free Energy of Dissolution fit in AP Chemistry?
Free Energy of Dissolution is topic 9.6 in Unit 9: Thermodynamics and Electrochemistry of AP Chemistry.
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