CHEM 210 1nd Edition Lecture 21 Outline of Last Lecture I. Energy Flow and Chemical ChangeA. ThermodynamicsOutline of Current Lecture II. ThermodynamicsA. EnergyB. EnthalpyCurrent LectureAs we learned in the previous lecture notes, thermodynamics is the study of heat and itstransformations. First Law of Thermodynamics:The first law of thermodynamics states that energy cannot be created nor destroyed. Energy in the universe is constant, and can be transferred from the system to the surroundings, or from the surroundings to the system.The equation we would use is ΔE universe = ΔE system + ΔE surroundings Or q + w = ΔEIn the second equation, if q and w are both positive, delta E will also be positive. If q is positive and w is negative, or vice versa, the sign of delta E would depend on the sizes of q and w. The biggest number or size will also be the sign of delta E. Finally, if q and w are both negative, deltaE will also be negative. These 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 positive q indicates the system gained heat, while a negative q indicates a system lost heat.A positive w indicates work was done on a system, while a negative w means work was done by the system. Units of Energy:- Joule (J) 1 J = 1Kg m2/s2- calorie (cal) 1 cal = 4.18 J- British Thermal Unit (Btu) 1 Btu = 1,055 JEnthalpy:Enthalpy is represented by the letter H. It is the sum of the internal energy and the product or volume of pressure. w = -PAVH = E + PVΔH = ΔE + PΔV ΔH > 0 = endothermic ΔH < 0 =
View Full Document
Unlocking...