Gas Law Applications Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.
Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of...
-
date post
21-Dec-2015 -
Category
Documents
-
view
218 -
download
0
Transcript of Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of...
![Page 1: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/1.jpg)
Please Pick Up
Dynamic Equilibria Problem Set
![Page 2: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/2.jpg)
Dynamic Equilibrium
Edward A. Mottel
Department of Chemistry
Rose-Hulman Institute of Technology
![Page 3: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/3.jpg)
04/18/23
Chemical Reactions inDynamic Equilibrium
• Reading Assignment: · Zumdahl Chapter 6.1-6.2
• Processes which do not proceed to completion, but which appear to stop on a macroscopic scale.
• The Law of Mass Action and the equilibrium constant are introduced as means to interpret this process.
![Page 4: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/4.jpg)
04/18/23
Dynamic versus Static Equilibrium
There are alwaystwo children in front
of the chairs.
The forces on both sidesof the teeter-totter
are the same.
![Page 5: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/5.jpg)
04/18/23
Dynamic Equilibrium
There is both a forward and reverse process. The process can be described with an
equilibrium arrow (actually two arrows).
favorableunfavorable equallyfavorable
![Page 6: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/6.jpg)
04/18/23
Dynamic Equilibrium Forward rate equals reverse rate.
Not all reactions are 100% complete. Note: it does not mean that
• reactants and products are equally stable.• reactants and products have the same or
equal concentrations.
H2O (l) H2O (g)H2O
H2O
![Page 7: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/7.jpg)
04/18/23
Law of Mass-ActionMass-Action Expression
Concentration or Pressure of Each Product
Concentration or Pressure of Each ReactantQ =
Reaction Quotientuses the currentconcentrationsor pressures
If the reactants andproducts are in dynamic
equilibrium, the ratio equalsthe Equilibrium Constant
= K
![Page 8: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/8.jpg)
04/18/23
Mass-Action Expression
• Balance the equation• Write the mass-action expression
· products over reactants
Hydrogen gas reacts with oxygen gas to give steam.
![Page 9: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/9.jpg)
04/18/23
Mass-Action Expression
Write the mass-action expression
Carbon dioxide gas dissolves in water to giveaqueous carbon dioxide.
![Page 10: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/10.jpg)
04/18/23
Mass-Action Expression
CO2(g) CO2(aq)
Q[ ]CO2
( )PCO2
=
square bracketsare used to indicate
molar concentrations
What would bethe units of thismass-action expression?
Carbon dioxide gas dissolves in water to giveaqueous carbon dioxide.
![Page 11: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/11.jpg)
04/18/23
The Reaction Quotient
The pressure of CO2 gas is 2.0 atm
The concentration of CO2 is 0.0030 M
What is the numeric value of the reaction quotient?
![Page 12: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/12.jpg)
04/18/23
Determining If a System is at Equilibrium
The equilibrium constant for CO2 gas dissolved in water is 3.4 x 10-2 M·atm-1
Q[ ]CO2
( )PCO2
= =0.0030 M
2.0 atm= 1.5 x 10-3 M·atm-1
Is the reaction at equilibrium?What must occur to attain equilibrium?
![Page 13: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/13.jpg)
04/18/23
Equilibrium Constant
K = Q when the system is at equilibrium
Special equilibrium constants
• K or Keq no special conditions
• Kp partial pressures
• Kc molarity concentrations
![Page 14: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/14.jpg)
04/18/23
Mass-Action Expression
CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO¯(aq)
K = [CH3COOH] [H2O]
[H3O+] [CH3COO¯]
Write the mass-action expression for the reaction ofaqueous acetic acid with water
to give hydronium ion and acetate ion.
![Page 15: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/15.jpg)
04/18/23
Mass-Action Expression Simplifications
If the concentration of a reactant or product does not or cannot vary, the mass-action expression can usually be simplified.
The term which doesn’t vary is “constant” and becomes part of the K.
A special subscript for K is added
![Page 16: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/16.jpg)
04/18/23
CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO¯(aq)CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO¯(aq)
K = [CH3COOH] [H2O]
[H3O+] [CH3COO¯]
[CH3COOH] [H2O]
[H3O+] [CH3COO¯]
Mass-Action Expression Simplifications
What is the molarity of water in pure water?
In this equation which terms can vary?(i.e., which can have different concentrations)
![Page 17: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/17.jpg)
04/18/23
[CH3COOH]
[H3O+] [CH3COO¯]
Mass-Action Expression Simplifications
CH3COOH(aq) + H2O(l)
[H2O] · K =
H3O+(l) + CH3COO¯(aq)CH3COOH(aq) + H2O(l)
= Ka
Ka is the acid dissociation constant.
![Page 18: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/18.jpg)
04/18/23
Mass-Action Expression Simplifications
solvent insoluble or sparingly soluble solid insoluble or sparingly soluble liquid
![Page 19: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/19.jpg)
04/18/23
Write the Simplified Mass-Action Expression for
Aqueous iron(III) ion reacts with water to give insoluble iron(III) hydroxide and aqueous hydrogen ions.
• Write a balanced and annotated equation• Write the mass-action expression• Simplify the mass-action expression
![Page 20: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/20.jpg)
04/18/23
Simplified Mass-Action Expression
Fe(OH)3(s) + 3 H+(aq)Fe3+(aq) + 3 H2O(l)
[Fe3+]
[H+]3
= Keq use Keq if youaren’t sure what
to call the constant
Why isn’t water in the mass-action expression?
Why isn’t Fe(OH)3 in the MAE
![Page 21: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/21.jpg)
04/18/23
Factors Which May Result in a System Failing to Attain Equilibrium
Reaction coordinate diagram Thermodynamic stability Kinetic stability
• activation energy• catalyst
![Page 22: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/22.jpg)
04/18/23
Factors Which May Result in a System Failing to Attain Equilibrium
Ene
rgy
Reactants Products
Reaction CoordinateDiagram
ThermodynamicallyUnstable
2 H2(g) + O2(g)2 H2O(g)
![Page 23: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/23.jpg)
04/18/23
Ene
rgy
Reactants Products
Reaction CoordinateDiagram
Factors Which May Result in a System Failing to Attain Equilibrium
ThermodynamicallyStable
Large activation barrier
The activation barrier may be overcomeby heating the reactants
![Page 24: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/24.jpg)
04/18/23
Ene
rgy
Reactants Products
Reaction CoordinateDiagram
Large activation barrier
Factors Which May Result in a System Failing to Attain Equilibrium
The activation barriermay be lowered by
the addition of a catalyst.
![Page 25: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/25.jpg)
04/18/23
![Page 26: Please Pick Up Dynamic Equilibria Problem Set. Dynamic Equilibrium Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology.](https://reader030.fdocuments.net/reader030/viewer/2022032521/56649d5f5503460f94a403d3/html5/thumbnails/26.jpg)
04/18/23