CH 302 1st Edition Lecture 3 Outline of Last Lecture I. Quick RemindersII. Vapor PressureIII. Phase diagramOutline of Current Lecture I. Important RemindersII. Entropy and Free Energy of DissolutionCurrent LectureImportant Reminders:- Vapor pressure of a liquid increases with increasing temperature- Lower IMFs mean higher vapor pressures- At the triple point, the solid, liquid, and gas all have the same free energy- Solution = solvent + solute- Solubility: how much dissolves in concentration- Dissolution: The process of making solution dissolving- When a solute dissolve spontaneously in a solvent, the process is considered spontaneous- In some cases, non-spontaneous dissolution process can become spontaneous upon increasing temperatureEntropy and Free Energy of Dissolution:What is going on with the entropy of dissolution?- The entropy always increases - The entropy of a solution is usually easy to predict- Solutions typically have higher entropy than the unmixed compoundsWhat is the free energy change for gases mixing?- Delta G is negative, therefore it is spontaneousWhy does the free energy decrease?- Delta H is zero and Delta S is positive- G = H – TS- Therefore this means that spontaneous dissolution must be entropically drivenWhat is the sign for the change in free energy for the dissolution process in which polystyrene peanuts were placed in water?- Positive because the process was nonspontaneousWhat is the sign for the change in entropy for the dissolution process in which polystyrene wereplaced in acetone?- PositiveWhat is the sign for the change in enthalpy for the dissolution process in which biodegradable peanuts were placed in acetone?- Positive because G is positive and S is positive (G = H –
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