Chapter_15-Equilibrium

Chapter_15-Equilibrium - Ch.14. Equilibrium. Equilibrium...

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Equilibrium Ch.14. Equilibrium.
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Equilibrium Ch.14. Equilibrium. N 2 O 4 ( g ) 2NO 2 ( g ) Concentratons Rates Equilibrium is reached when the rates of the forward and reverse reactions become equal.
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Reaching the equilibrium Ch.14. Equilibrium. N 2 ( g ) + 3H 2 ( g ) 2NH 3 ( g ) Forward reaction Reverse reaction The equilibrium can be reached from either direction.
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The law of mass action. Equilibrium constant Ch.14. Equilibrium. aA + bB dD + eE [D] d [E] e K c =  [A] a [B] b C.M.Guldberg and P.Waage, 1864 Equilibrium constant All concentrations are expressed in M, not in mM, μ M etc Reactants in the denominator Products are placed in the numerator Equilibrium-constant expression
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The law of mass action. Equilibrium constant Ch.14. Equilibrium. aA + bB dD + eE [D] d [E] e K c =  [A] a [B] b The equilibrium-constant expression depends only on the stoichiometry of the reaction, not on its mechanism
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The law of mass action. Equilibrium constant Ch.14. Equilibrium. N 2 O 4 ( g ) 2NO 2 ( g ) [NO 2 ] 2 K c =  [N 2 O 4 ] K c depends on temperature and does not depend on initial concentrations of the reactants [N 2 O 4 ] initial [NO 2 ] initial [N 2 O 4 ] equilibrium [NO 2 ] equilibrium K c At 100°C
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Equilibrium constant for gases Ch.14. Equilibrium. For gaseous reactants and products instead of concentrations we often use partial pressures, in atm units. Numerical value for K p can be different from that for K c aA + bB dD + eE P D d P E e K p =  P A a P B b K p = K c (RT) n , where n=d+e-(a+b) Equilibrium constant in terms of pressure.
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Units of equilibrium constants Ch.14. Equilibrium. Equilibrium constants are always dimensionless , independently how many products and reactants are in the reaction. By the rule the concentrations used in equilibrium- constant expression are in fact expressed not in M, but rather they are referenced to a standard concentration 1M – this is called the activity of a substance: Activity = [A]/1M or Activity = P A / 1 atm
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Interpreting equilibrium constants. Value of
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This note was uploaded on 01/02/2012 for the course CHEM 114 taught by Professor Sergeiaksyonov during the Fall '11 term at ASU.

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Chapter_15-Equilibrium - Ch.14. Equilibrium. Equilibrium...

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