handout_L01_Energy_Enthalpy

Handout_L01_Energy_E - Lecture 1A Energy Reading Zumdahl 9.1 Outline Energy Kinetic and Potential System vs Surroundings Heat Work and Energy h m

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Lecture 1A: Energy • Reading: Zumdahl 9.1 • Outline – Energy: Kinetic and Potential – System vs. Surroundings – Heat, Work, and Energy Energy: Kinetic vs. Potential • Potential Energy (PE) – Energy due to position or composition. – Equals (mgh) in example. • Kinetic Energy (KE) – Energy due to motion. – Equals mv 2 /2 in example. h m v Energy = KE + PE • Energy is the sum of kinetic energy and potential energy. • Energy is readily interconverted between these two forms. • If the system of interest is isolated (no exchange with surroundings), then total energy is constant. Example: Mass on a Spring • Initial PE = 1/2 kx 2 • At x = 0: –P E = 0 – KE = 1/2mv 2 =1/2kx 2 • Units of Energy Joule = kg.m 2 /s 2 •E x am p l e : – Init. PE = 10 J – M = 10 kg – Vmax = [2(PE)/M] 1/2 = 1.4m/s 0 First Law of Thermodynamics First Law: Energy of the Universe is Constant E = q + w (remember this) q = heat. Transferred between two bodies of differing temperature. Note: q Temp! w = work. Force acting over a distance (F x d) Applying the First Law • Need to differentiate between the system and surroundings. • System: That part of the universe you are interested in (i.e., you define it). • Surroundings: The rest of the universe. System Surroundings q transfer w transfer
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Conservation of Energy • Total energy is conserved. • Energy gained by the system must be lost by the surroundings. • Energy exchange can be in the form of q, w, or both. P = 1atm P = 1atm Initial Final Heat Exchange: Exothermic • Exothermic Reaction. Chemical process in which system evolves resulting in heat transfer to the surroundings. • q < 0 (heat is lost) E n e r g y Einitial Efinal Efinal < Einitial Water @ 80° C Water @ 20° C q Another Example of Exothermic Heat Exchange: Endothermic • Endothermic Reaction: Chemical process in which system evolves resulting in heat transfer to the system.
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This note was uploaded on 01/18/2012 for the course CHEM 152A taught by Professor Chiu during the Winter '12 term at University of Washington.

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Handout_L01_Energy_E - Lecture 1A Energy Reading Zumdahl 9.1 Outline Energy Kinetic and Potential System vs Surroundings Heat Work and Energy h m

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