15 Chemical Equilibrium

15 Chemical Equilibrium - Which equation do you use to...

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1 If a reaction rate increases by 10 times when the temperature is raised from 20 o C to 30 o C, what is the activation energy for the reaction? -1 -1 8.314 J mol K R 0 o C = 273 K Which equation do you use to determine the activation energy given how the reaction rate changes from one temperature to another? See the example below. 2 11 2 1 22 1 A) ln B) ln C) either one, A and B are equivalent a a E k kR T T E k T T     a E RT k = A e 2 2 2 1 1 A) ln B) ln a a E k T T E k T T You can assign the high T, 303 K, to either T 1 or T 2 . If T 1 = 303 K, then T 2 = 293 K, and k 1 = 10 x k 2 2 2 2 2 A) ln 10 x 303 293 10 x 1 1 B) ln 293 303 a a E k E k Both give E a = 170 kJ/mol Multiply both sides of (A) by -1 to obtain (B)!

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3 Ch 14 Chemical Equilibrium Reviews some issues previously discussed. Introduces some new issues. Key questions! What do we mean by chemical equilibrium? How is it connected to chemical kinetics? How is it connected to thermodynamics? How are the ideas of equilibrium and equilibrium constants used? 4 For this gas phase reaction, when do you think equilibrium has been reached, and the concentration of the products stops increasing? A) When all the reactant has been consumed. B) When the rate constant for the forward reaction equals the rate constant for the reverse reaction. C) When the products are converted into the reactant at the same rate as the reactant is being converted back into products, so the concentrations no longer change. 2NO 2 2NO + O 2 What do we mean by chemical equilibrium?
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This note was uploaded on 02/13/2011 for the course CHE 132 taught by Professor Hanson during the Spring '08 term at SUNY Stony Brook.

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15 Chemical Equilibrium - Which equation do you use to...

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