SI THERMO

# SI THERMO - Chapter 6 Thermodynamics Yashar Niknafs First...

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Chapter 6: Thermodynamics Yashar Niknafs First law of thermodynamics = energy can be converted from one form to another, but cannot be created or destroyed Enthalpy = total heat content of system Exothermic  = negative… heat leaves system surroundings Endothermic  = positive… heat enters system surroundings Hess’s Law = states that overall enthalpy change in a reaction = sum of enthalpies of formation of products and reactants ΔE = q + w o Change in energy of system = (heat exchange) + (work done) W = -PΔV o work done = - (pressure) x (volume) ΔH = ΔE + PΔV o Enthalpy = (change in energy of system) + (pressure) x (volume) C = ms OR C = mc --------- s = c = specific heat o Heat capacity = (mass) x (specific heat) q = mcΔt OR msΔt o heat exchange = (mass) x (specific heat) x (change in temperature) q = CΔt o heat exchange = (heat capacity) x (change in temperature) q = nΔH o heat exchange = () x (change in enthalpy) q rxn = - q cal - q water

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o heat exchange of reaction = - (heat exchange of calorimeter) – (heat exchange of water) GENEARL THERMOCHEMISTRY : 1. If a gas absorbs 234 J of heat and is compressed by 534 J of work. What is the internal energy change? 2. If a gas is cooled by removing 106 J of heat and expands doing 242 J of work. What is the internal energy change? 3. If a gas expands from 0.250 L to 1.00 L against an external pressure of 2.50 atm. How much work is done? 4. If the change in internal energy for a constant pressure process was -407J
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## This note was uploaded on 03/01/2009 for the course CHEM 105 taught by Professor Kenney during the Spring '08 term at Case Western.

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SI THERMO - Chapter 6 Thermodynamics Yashar Niknafs First...

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