Lecture_33_113011 - Lecture 33 Le Chtelier's Principle...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 33: Le Châtelier’s Principle Goals: Use an equilibrium constant to predict the extent of reaction and to calculate equilibrium concentrations. Use Le Chatelier’s principle to describe the changes made in equilibrium when reaction conditions change. Outline (Timberlake 9.4-9.5): ± Using Equilibrium Constants (9.4) ± Changing Equilibrium Conditions: Le Châtelier’s Principle (9.5) Problems for Extra Practice: 9.21, 9.23, 9.25, 9.27, 9.29, 9.31
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Reaching Chemical Equilibrium A container initially filled with SO 2 ( g ) and O 2 ( g ) or only SO 3 ( g ) • contains mostly SO 3 ( g ) and small amounts of O 2 ( g ) and SO 3 ( g ) at equilibrium • reaches equilibrium in both situations
Background image of page 2
EQUILIBRIUM Changes of concentrations of reactant and product during chemical reaction. Equilibrium concentrations will yield K value. Kinetics of Chemical Reactions TIME
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Initial and Equilibrium Concentrations for the N 2 O 4 -NO 2 System at 100 ° C Initial Equilibrium Ratio [N 2 O 4 ] [N 2 O 4 ] [N 2 O 4 ] [NO 2 ] [NO 2 ] [NO 2 ] 2 0.1000 0.0000 0.0491 0.1018 0.211 0.0000 0.1000 0.0185 0.0627 0.212 0.0500 0.0500 0.0332 0.0837 0.211 0.0750 0.0250 0.0411 0.0930 0.210 =K Experiments carried out at a certain temperature, but with different initial concentrations, yield the same value for the EQUILIBRIUM CONSTANT, K .
Background image of page 4
Equilibrium Can Favor Product If equilibrium is reached after most of the forward reaction has occurred, • the system favors the products
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Equilibrium with a Large K c At equilibrium, • a reaction with a large K c produces a large amount of product; very little of the reactants remain K c = [NCl 3 ] 2 = 3.2 x 10 11 [N 2 ][Cl 2 ] 3 • a large K c favors the products N 2 ( g ) + 3Cl 2 ( g ) 2NCl 3 ( g ) When this reaction reaches equilibrium, it will essentially consist of the product NCl 3 .
Background image of page 6
Equilibrium Can Favor Reactant If equilibrium is reached when very little of the forward reaction has occurred, • the reaction favors the reactants
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Equilibrium with a Small K c At equilibrium, • a reaction that produces only a small amount of product has a small K c K c = [NO] 2 = 2.3 x 10 -9 [N 2 ][O 2 ] • a small K c favors the reactants N 2 ( g ) + O 2 ( g ) 2NO( g ) When this reaction reaches equilibrium, it will essentially consist of the reactants N 2 and O 2 .
Background image of page 8
Summary of K c Values A reaction • that favors products has a large K c • with about equal concentrations of products and reactants has a K c close to 1 • that favors reactants has a small K c
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Summary of K c Values (continued)
Background image of page 10
Large and Small K c Values
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
For each K c , indicate whether the reaction at equilibrium contains mostly of (R) reactants or (P) products. _______A.
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 45

Lecture_33_113011 - Lecture 33 Le Chtelier's Principle...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online