University College - Chemistry Chem 112A Lecture Notes - Lecture 7: Boltzmann Constant, Isothermal Process, Spontaneous Process
7 Mar 2016
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Document Summary
State functions: change in value between initial and final states only depends on the states, not how the change is made. Hess" law: when two or more chemical reactions are added together to make a new reaction, their enthalpies of reaction can be added together to find the enthalpy of the new reaction. Enthalpy = sum of enthalpy of products - sum of enthalpy of reactants. (all include coefficients as related to the reaction. H_i (t) = molar enthalpy of substance i. Elements in their standard states: the most stable form of the pure element at 1 atm, 298k. Enthalpy change upon formation of 1 mole of substance from its elements in their standard states: (deltah_r) = deltah_f = enthalpy of formation: Delta(h_r (t)) = sum of the enthalpies of formation of products - sum of the enthalpies of formation of reactants.
