Section 19.3 Free Energy, the Reaction Quotient and the Equilibrium Constant Bill Vining SUNY College at Oneonta.

Slides:



Advertisements
Similar presentations
Chapter 7: Chemical Equilibrium. 7.1 The Gibbs energy minimum 1. Extent of reaction ( ξ ): The amount of reactants being converted to products. Its unit.
Advertisements

Entropy and Free Energy Chapter 19. Laws of Thermodynamics First Law – Energy is conserved in chemical processes neither created nor destroyed converted.
Equilibrium II 15.6 – Using Keq 15.7 – Le Chậtelier’s Principle
Free Energy and Equilibrium  G of a reaction (run at standard conditions,  G  ) is the change in free energy accompanying the chemical reaction in which.
Chemical equilibrium. Forward and reverse reactions Not all chemical reactions occur in one direction. They can go “forward” – to the right. They can.
Chemical Equilibrium. Rate of forward Rx = Rate of reverse Rx As a system approaches equilibrium, both the forward and reverse reactions are occurring.
Equilibrium Basic Concepts Reversible reactions do not go to completion. –They can occur in either direction Chemical equilibrium exists when two opposing.
Chemical Thermodynamics: Entropy, Free Energy and Equilibrium Chapter
Chemical Thermodynamics BLB 12 th Chapter 19. Chemical Reactions 1. Will the reaction occur, i.e. is it spontaneous? Ch. 5, How fast will the reaction.
Chapter 19 Chemical Thermodynamics John D. Bookstaver St. Charles Community College St. Peters, MO 2006, Prentice Hall, Inc. Modified by S.A. Green, 2006.
Daniel L. Reger Scott R. Goode David W. Ball Chapter 17 Chemical Thermodynamics.
THERMODYNAMICS: ENTROPY, FREE ENERGY, AND EQUILIBRIUM Chapter 17.
Chapter 18: Thermodynamics Renee Y. Becker Valencia Community College.
Entropy, Free Energy, and Equilibrium Chapter 19 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Equilibrium – Where? vs. Why? The value of K is an indication of WHERE the equilibrium rests. We haven’t addressed WHY the equilibrium exists where it.
18-1 CHEM 102, Spring 2012 LA TECH CTH :00-11:15 am Instructor: Dr. Upali Siriwardane Office: CTH 311 Phone Office.
Thermodynamic Connection Q and G and letters other than K.
AP Chapter 19.  Energy can not be created nor destroyed, only transferred between a system and the surroundings.  The energy in the universe is constant.
System strives for minimum Free Energy. aA + bB cC + dD G0G0 rxn d  G 0 (D) f c  G 0 (C) f = [+] - b  G 0 (B) f a  G 0 (A) f [+] G0G0 rxn n 
GOES WITH CHAPTER 17: SILBERBERG; PRINCIPLES OF GENERAL CHEMISTRY AP CHEMISTRY MRS. LAURA PECK Topic 12: Equilibrium 1.
Reversible Reactions Reactions are spontaneous if  G is negative. If  G is positive the reaction happens in the opposite direction. 2H 2 (g) + O 2 (g)
Second Law of Thermodynamics. Law of Disorder the disorder (or entropy) of a system tends to increase ENTROPY (S) Entropy is a measure of disorder Low.
 FACT: ∆G o rxn is the change in free energy when pure reactants convert COMPLETELY to pure products.  FACT: Product-favored systems have K eq > 1. 
Section 19.1 Entropy and the Three Laws of Thermodynamics
Chapter 15 Equilibrium. © 2009, Prentice-Hall, Inc. The Concept of Equilibrium Chemical equilibrium occurs when a reaction and its reverse reaction proceed.
EQUILIBRIUM CHEMICAL. Chemical Equilibrium Reversible Reactions: A chemical reaction in which the products can react to re-form the reactants Chemical.
Marie Benkley June 15, 2005 Equilibrium is a state in which both the forward and reverse reactions occur at equal rates. No net change is observed at.
Chapter 15 Chemical Equilibrium
Entropy and Free Energy (Kotz Ch 20) - Lecture #2
1 CHEMICAL EQUILIBRIUM Chapter 16. “Systems”: two reactions that differ only in direction Any reversible reaction H 2 + I 2 ↔ 2HI noted by the double.
 Because entropy is a state function, the property is what it is regardless of pathway, the entropy change for a given reaction can be calculated by taking.
1 HOW ARE EQUILIBRIUM EXPRESSIONS WRITTEN? Q VS. K.
When components of a reaction are mixed, they will proceed, rapidly or slowly (depending on kinetics) to the equilibrium position. Equilibrium position:
 G 0 system =  H 0 system - T  S 0 system  G 0 rxn =  m  G 0 products -  n  G 0 reactants.
Maximum Work 1 Often reactions are not carried out in a way that does useful work. –As a spontaneous precipitation reaction occurs, the free energy of.
Entropy Changes in Chemical Reactions.  Because entropy is a state function, the property is what it is regardless of pathway, the entropy change for.
Chemical Equilibrium Reactants Products Reactants Products As the time increases… [Reactants] decrease, so the rate of forward reaction decreases; [Products]
Chapter 16: Chemical Equilibrium. © 2009, Prentice-Hall, Inc. The Concept of Equilibrium Chemical equilibrium occurs when a reaction and its reverse reaction.
6-1 Unlike  H,  E, or  S…  G depends on amounts of reactants and products present………This is a parameter characterized by the letter Q (reaction quotient)
Chapter 19 Spontaneity, entropy and free energy (rev. 11/09/08)
Obj 15.1, The concept of Equilibrium A.) Chemical equilibrium occurs when a reaction and its reverse reaction proceed at the same rate.
1 Vanessa N. Prasad-Permaul Valencia College CHM 1046.
Ch. 19: Spontaneity (“Thermodynamically Favored”), Entropy and Free Energy.
H.W. # 20 Study pp Ans. Ques. p. 826 # 65,67,71,79 Aim # 20: What is the relationship between free energy and.
Chapter 9 Chemical Equilibrium
Free Energy and Equilibrium
Spontaneity, Entropy, and Free Energy
Chapter 19 Chemical Thermodynamics
Topic 7- Equilibrium.
Section 19.1 Entropy and the Three Laws of Thermodynamics
Chemical Equilibrium.
CH 19: Thermodynamics.
Thermodynamic Connection
Thermodynamics and Keq
Section 19.3 Free Energy, the Reaction Quotient and the Equilibrium Constant Bill Vining SUNY College at Oneonta.
CHEMICAL EQUILIBRIUM.
CHEMICAL EQUILIBRIUM Chapter 13
Sections Equilibrium and the Equilibrium Constant
CHEMICAL EQUILIBRIUM.
Reaction quotient, Q In an equilibrium system, all substances must be present. When only “reactants” are provided, the system is clearly not at equilibrium.
Chemical Equilibrium.
CH 19: Thermodynamics.
13.1 CHEMICAL EQUILIBRIUM Cato Maximilian Guldberg and his brother-in-law Peter Waage developed the Law of Mass Action.
Chemical Equilibrium.
CHEMICAL EQUILIBRIUM.
THERMODYNAMICS #1 Example of using standard heats of formation to get ∆H of reaction Calculate the heat of reaction for the following combustion. 4 NH3.
Free Energy and the Equilibrium Constant
Gibbs Free Energy.
Chemical Equilibrium Reversible Reactions:
Presentation transcript:

Section 19.3 Free Energy, the Reaction Quotient and the Equilibrium Constant Bill Vining SUNY College at Oneonta

Recall Q, K and Reaction Favorability Q < K The system is not at equilibrium. Reactants will be consumed, and product concentration will increase until Q = K. The reaction will proceed in the forward direction as written (reactants  products). The system is at equilibrium, and no further change in reactant or product concentration will occur. The system is not at equilibrium. Products will be consumed, and reactant concentration will increase until Q = K. The reaction proceeds to the left as written (reactants  products). Q = K Q > K

 G determines if the reaction system in its current state is spontaneous in either direction.  G o determines if the system is product-favored or reactant-favored. Q represents the current state of the system.  G,  G o and Q  G < 0 Reaction is spontaneous in the forward direction (reactants  products). Reaction is at equilibrium. Reaction is spontaneous in the reverse direction (reactants  products).  G = 0  G > 0  G o < 0 Reaction is product-favored. Reaction is neither reactant- or product-favored.. Reaction is reactant-favored.  G o = 0  G o > 0

Connecting  G,  G o and Q  G =  G o + RT lnQ Use standard thermodynamic data (linked) to calculate  G at K for the following reaction, assuming that all gases have a pressure of mm Hg. 2NO(g) + O 2 (g)  2NO 2 (g)  G f o (kJ/mol) NO(g) 86.6 O 2 (g) 0 NO 2 (g) 51.3

Connecting  G,  G o and Q  G =  G o + RT lnQ Use standard thermodynamic data (linked) to calculate  G at K for the following reaction, assuming that all gases have a pressure of mm Hg. 2NO(g) + O 2 (g)  2NO 2 (g)  G f o (kJ/mol) NO(g) 86.6 O 2 (g) 0 NO 2 (g) 51.3

 G,  G o and the Equilibrium Constant, K At equilibrion,  G = 0 so 0 =  G o + RT ln Q  G o =  RT ln Q and Use standard thermodynamic data to calculate K at K for the following reaction. 2NO(g) + O 2 (g)  2NO 2 (g)  G f o (kJ/mol) NO(g) 86.6 O 2 (g) 0 NO 2 (g) 51.3  G o = kJ

 G,  G o and the Equilibrium Constant, K A student determines the value of the equilibrium constant to be 1.11E6 for the following reaction. 3Fe 2 O 3 (s) + H 2 (g)2Fe 3 O 4 (s) + H 2 O(g) Based on this value of K eq :  G° for this reaction is expected to be (greater, less) than zero. Calculate  G° and the free energy change for the reaction of 1.67 moles of Fe 2 O 3 (s) at standard conditions at 298K.

 G,  G o, Q, and K

Can a chemical system have a positive value of  G o and yet still be favored to react in the forward direction?