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Unformatted text preview: Chem 6B Equation Sheet (Exam 3) 1 Prof. Crowell Chem 6B Final Exam Equation Sheet 1st Law : the total amount of energy in the universe is constant (energy is conserved). U q w = + = + = + = + 2nd Law : in any spontaneous change the entropy of the universe increases. universe S > > > > 3rd Law : the entropy of any pure, perfect crystalline solid at absolute zero is zero. system S at K = D An open system can exchange both matter & energy with its surroundings. A closed system can exchange energy with the surroundings but not matter. An isolated system cannot exchange energy nor matter. Diathermic Walls allow energy to flow as heat if there is a temperature difference between the system & surroundings, whereas Adiabatic Walls do not. Reversible Process A process involving a series of infinitesimal changes . At each step in a reversible process, the system is in mechanical equilibrium (e.g. P or T) with its surroundings. Irreversible Process A process in which change occurs by finite amounts. The work done in the expansion process approaches the reversible process as the number of steps becomes larger. The maximum work done in an expansion is during a reversible process. Sign convention: heat & work are both positive when they enter the system & negative when they leave the system. Ideal gas law: ; PV nRT = 2 2 3 work = force distance = N-m = kg-m /s = Pa-m = J; Expansion work = ext w P V = = = = Isothermal Constant Temperature with corresponding changes in Pressure , Volume , and with Heat added or removed. ; reversible work: ln ; final init V PV const w nRT T U q w V = = = = = = = = = = = = = = = = = = = = Isobaric Constant Pressure with corresponding changes in Volume , Temperature , and with Heat added or removed. , , ; ; P m P m w P V q n C T U q w P V n C T = = = + = + = = = + = + = = = + = + = = = + = + Isosteric (or Isochoric ) Constant Volume with corresponding changes in Pressure , Temperature , & with Heat added or removed. , , 0 since 0; ; V m p m w V q n C T U q w n C T = = = = + = = = = = + = = = = = + = = = = = + = Adiabatic Constant Heat (No Heat Flow) with corresponding changes in Pressure , Volume , and Temperature .-1 P V C 1 constant; also constant; V constant; with = ; C PV TV T + = = = = = = = = = = = = = = = = Adiabatic: ; using we find q U w w P d V U w n R T = = = = = = = = = = = = = = = = = Heat is the transfer of energy as a result of a temperature difference. Exothermic processes release heat & Endothermic processes absorb heat. Calorimetry is the measurement of heats of rxn using heat capacity:...
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- Winter '08