CHEM 1125Q 1st Edition Lecture 14 Outline of Last Lecture Ch. 14I. Spontaneous Process, EntropyOutline of Current Lecture Ch. 14II. Standard EntropyA. Standard EntropyB. Qualitative PredictionsC. Entropy ChangesD. Calculating Entropy of SurroundingsCurrent LectureII. Standard EntropyA. Standard Entropya. Standard Entropy in a substance’s absolute entropy at 1atm, S0b. Since temperature is not part of the standard state definition, it needsto be specifiedc. Under normal conditions, S0 can never equal 0d. Entropy increases with temperature, number of atoms, molar mass, molecular complexity, and mobility of the phasei. S0liquid S0solidii. S0gas S0liquidB. Qualitative Predictionsa. Processes that lead to an entropy increase include:i. Melting, vaporization, and sublimationii. Increase in temperatureiii. Any reaction resulting in an increase in the number of gas moleculesb. The process of dissolving a substance can lead to either an increase ordecrease in entropy, depending on the solute’s naturei. Molecular = increaseii. Ionic = increase or decreaseC. Entropy Changesa. In order to predict spontaneity, we need to consider changes for both the system and the surroundingsi. ΔSuniverse = ΔSsystem + ΔSsurroundingsD. Calculating Entropy of SurroundingsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. ΔSsurroundings is directly proportional to ΔHsystemi. ΔSsurroundings = -ΔHsystem /Tb. According to the 2nd Law of Thermodynamics, ΔSuniverse must be positive in order for a process to be spontaneousi. ΔSuniverse = ΔSsystem + ΔSsurroundingsii. ΔSuniverse > 0 for a spontaneous processiii. ΔSuniverse < 0 for a nonspontaneous processiv. ΔSuniverse = 0 for an equilibrium
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