Ch_322a_3.013

Ch_322a_3.013 - The Equilibrium Constant and Free Energy...

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The Equilibrium Constant and Free Energy Changes Gibbs Free Energy The change in free energy, ! G , for a chemical reaction indicates if it is spontaneous, if it proceeds without the input of work from the surroundings. If ! G is negative , the reaction in the forward direction proceeds spontaneously . If ! G is zero , the reaction is at equilibrium , there is no net driving force in the forward or reverse direction. If ! G is positive , the forward reaction will not proceed without input of work from the surroundings. Late in the 19th century, Josiah Williard Gibbs (1839-1903) proposed a new function of chemical states that describes the spontaneity of a chemical reaction. Today, this state function is called the Gibbs Free Energy or simply the Free Energy , G .
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The Gibbs State Function Gibbs defined his new state function in terms of two existing thermodynamic state functions: enthalpy , H , and entropy , S . G = H - T S and the change in free energy for a reaction is ! G = ! H - T ! S Standard Free Energy Change, ! G o Because free energy is a state function, like enthalpy and entropy, it is possible to calculate the free energy of substances under standard conditions , ! G o . Standard Conditions of Substances state of matter standard state solid pure solid liquid pure liquid gas 1 atm solution 1 M concentration elements The standard free energy of formation of an element is defined as zero.
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Ch_322a_3.013 - The Equilibrium Constant and Free Energy...

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