CHEM 102 1nd Edition Lecture 4Outline of Last Lecture I. EnthalpyII. Elements in standard stateIII. State functionIV. First law of thermodynamicsV. Spontaneous reactionsOutline of Current Lecture VI. Gibbs free energyVII. EnthalpyVIII. Elements in standard stateIX. State functionX. First law of thermodynamicsXI. Spontaneous reactionsCurrent Lecture- Gibbs Free energy, G: thermodynamic state function of a system which indicates the amount of energy available fro a system to do useful work- Enthalpy—heat content of a substance at constant pressureo Designated by Ho Delta H = Hfinal - Hinitialo Delta Hrxn = Delta Hprodutcs – Delta Hreactantso Sign convention Delta H>O—reaction process is endothermic (absorbs energy) Delta H<O—reaction process is exothermic (releases energy)- Elements in standard stateo State of an element when the pressure is 1 atm (760 mmHg) and temperature is 25 degrees C Hydrogen-H2 (g) Oxygen-O2 (g) Mercury-Hg (l) Tin-Sn (s) Carbon-C (graphite, s)- State function: a quantity whose value is determined only by the stat of a systemThese 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.o Changes in a state function depend only on intial and final state, and not on how the state was reached Pressure: P and Delta P Temperature: T and Delta T Volume: V and Delta V Enthalpy: H and Delta H- First law of Thermodynamics: the total energy of the universe is constant where system is understudy + surroundings = universe- Spontaneous reaction or process: one that occurs in the forward direction without intervention- Delta H alone does not determine if a reaction is
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