Ch 6_handouts - Chapter 6: Chemical Equilibrium 6.1 6.2 6.3...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
1 6.1 The Equilibrium Condition 6.2 The Equilibrium Constant 6.3 Equilibrium Expressions Involving Pressures 6.4 The Concept of Activity 6.5 Heterogeneous Equilibria 6.6 Applications of the Equilibrium Constant 6.7 Solving Equilibrium Problems 6.8 LeChatelier’s Principle 6.9 Equilibria Involving Real Gases Chapter 6: Chemical Equilibrium 2 Chemical Equilibrium So far, we have assumed that a chemical reaction goes to completion as written. CO( g ) + H 2 O ( g ) ˠ CO 2 (g) + H 2 ( g ) In general, this is not correct. Instead, a stable state of the system in reached, which includes both reactants and products at constant concentrations. It is called the equilibrium state, or simply “equilibrium”. CO( g ) + H 2 O ( g ) CO 2 (g) + H 2 ( g )
Background image of page 1

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

View Full DocumentRight Arrow Icon
3 Molecular Picture of Establishment of Equilibrium CO( g ) + H 2 O( g ) CO 2 ( g ) + H 2 ( g ) INITIAL 7 CO( g ) + 7 H 2 O( g ) + 0 CO 2 ( g ) + 0 H 2 ( g ) AFTER IT STOPS CHANGING 2 CO( g ) + 2 H 2 O( g ) + 5 CO 2 ( g ) + 5 H 2 ( g ) 4 Concentration vs. Time CO( g ) + H 2 O( g ) CO 2 ( g ) + H 2 ( g ) Ratio depends on temperature
Background image of page 2
5 Characteristics of Chemical Equilibrium States Reaching equilibrium requires that reactions occur. Once equilibrium is reached, there is no macroscopic evidence of further change. Reached through dynamic balance of forward and reverse reaction rates . Chemical reactions occur via collisions of reacting molecules. The energy released during collisions breaks bonds in reactant molecules, allowing the atoms to rearrange to form a product. 6 “Chemical equilibrium is the state at which the concentrations of all reactants and products remain the same” “ At chemical equilibrium the rate of formation and decomposition remains the same” “ When equilibrium favors product , equilibrium is shifted to the right 2 NO 2 (g) N 2 O 4 (g) Dimerization of nitrogen dioxide Decomposition of dinitrogen tetroxide CHEMICAL EQUILIBRIUM
Background image of page 3

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

View Full DocumentRight Arrow Icon
7 N 2 O 4 (g) 2 NO 2 (g) Colorless Brown DECOMPOSITION Reaching Equilibrium on the Macroscopic and Molecular Levels 8 2 NO 2 (g) N 2 O 4 (g) DIMERIZATION BROWN COLORLESS Reaction of 2 NO 2 ( g ) N 2 O 4 ( g )
Background image of page 4
9 Consider the following equation: CO( g ) + H 2 O( g ) CO 2 ( g ) + H 2 ( g ) Which of the following must be true at equilibrium? 1. [CO 2 ] = [H 2 ] because they are in a 1:1 mole ratio in the balanced equation. 2. The total concentration of reactants is equal to the total concentration of the products. 3. The total concentration of the reactants is greater than the total concentration of the products. 4. The total concentration of the products is greater than the total concentration of the reactants. 5. None of these is true. 5 10 K - equilibrium constant is based on LAW of MASS ACTION j A + k B l C + m D where A, B, C, D are chemical species and j, k, l, m are coefFcients K = [C] l [D] m [A] j [B] k NOTE: conc. of chemical species are at EQUILIBRIUM!! The “apparent units” for K are concentration units raised to some power = l+m–(j+k) K depends only on T , not on initial concentrations.
Background image of page 5

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

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/19/2012 for the course CHEM 142A taught by Professor Campbell during the Summer '11 term at University of Washington.

Page1 / 42

Ch 6_handouts - Chapter 6: Chemical Equilibrium 6.1 6.2 6.3...

This preview shows document pages 1 - 6. Sign up to view the full document.

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