🏷️ LIMITED TIME OFFER: GET 20% OFF GRADE+ YEARLY SUBSCRIPTION →
Log in
HomeClass Notes1,200,000AU40,000

CHEM1100 Lecture Notes - Lecture 18: Gibbs Free Energy, Spontaneous Process, Endergonic Reaction

81 views2 pages
blueclam798
25 May 2018
School
UQ
Department
Chemistry
Course
CHEM1100
Professor
Gwen Lawrie

For unlimited access to Class Notes, a Class+ subscription is required.

Lecture 18 - Spontaneity and Gibbs Free energy !
Gibbs free energy
•Is the amount of available energy in a system that can be used for work !
•Is the driving force for a chemical reaction because it considers both effects of enthalpy and
entropy !
•Will explain which direction a reaction will happen and if it will be endo or exothermic !
!
Some notes!
•∆G < 0 : spontaneous process
•∆G > 0 : reverse process is spontaneous
•∆G = 0 : equilibrium
•spontaneous reactions minimise free energy (because S will be larger in the equation
and will decrease the G
Standard Gibbs energy change
!
The amount of free energy in a reaction of compounds = how much energy is in the products -
how much energy was in the reactants. !
The energy in the reactants/products in the heat that was required to from each compound. This
is called the standard Gibbs energy of formation (ΔfG Ѳ )
•change in G when 1 mol of a substance is created from its constituent elements, with all species
being in their standard states. !
Gibbs free energy = - temperature x (change in entropy of the universe)
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Lecture 18 - spontaneity and gibbs free energy. Gibbs free energy = - temperature x (change in entropy of the universe) The amount of free energy in a reaction of compounds = how much energy is in the products - how much energy was in the reactants. The energy in the reactants/products in the heat that was required to from each compound. This is called the standard gibbs energy of formation ( fg : change in g when 1 mol of a substance is created from its constituent elements, with all species being in their standard states. Enthalpy is increased because melting ice is an endergonic reaction. But this reaction is only spontaneous at t>0. When t = 0, this reaction will be at equilibrium. Reactions that decrease the disorder (enthalpy) and increase the amount of energy in the system (the enthalpy) will never be spontaneous.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related textbook solutions

Chemistry: Structure and Properties
2 Edition,
Tro
ISBN: 9780134293936
Basic Chemistry
5 Edition,
Timberlake
ISBN: 9780134138046
Principles of Chemistry Molecular Approach
4th Edition,
Tro
ISBN: 9780134112831
Chemistry: Structure and Properties
2nd Edition,
Tro
ISBN: 9780134293936
Principles of Chemistry Molecular Approach
3rd Edition, 2014
Tro
ISBN: 9780321971944
Chemistry: A Molecular Approach
3rd Edition,
Tro
ISBN: 9780321809247
Chemistry: A Molecular Approach
5th Edition,
Tro
ISBN: 9780134874371
Principles of Chemistry: A Molecular Approach
4th Edition,
Tro
ISBN: 9780134895741
Chemistry: The Central Science
14th Edition, 2017
Brown
ISBN: 9780134414232

Related Documents

CHEM1100
Final Exam
Study Guide
CHEM1100 Study Guide - Boiling Point, Gibbs Free Energy, Lattice Energy
CHEM1100
Final Exam
Study Guide
CHEM1100 Study Guide - Boiling Point, Gibbs Free Energy, Lattice Energy
CHEM1100 Lecture Notes - Lecture 17: Standard Molar Entropy, Spontaneous Process, Thermodynamics
blueclam798

Related Questions

I need help on this chemistry work. Thanks.

DATA ANALYSIS

Using the example, calculate the Gibbs free energy for the process of dissolving ammonium nitrate and the process of dissolving sodium hydroxide (equation: ΔG = ΔH – TΔS).

Use the standard temperature 298 K.

Use the experimental data to calculate enthalpy of dissolving (ΔH).

Use the following data to calculate the entropy change (ΔS):

S (J/K mol)

NH4NO3(s)

151

NH4+(aq)

113.4

NO3-(aq)

146.4

NaOH(s)

64.46

Na+(aq)

59.0

OH-(aq)

- 10.7

After completing the calculations answer the following questions separately for each experiment:

Is the dissolving exothermic or endothermic?

Does the entropy decreases or increases during dissolving?

Is the Gibbs free energy positive or negative? Is the process of dissolving spontaneous?

Using data in the appendix in your textbook, calculate Gibbs free energy for the reaction of dissolving

lithium phosphate, Li3PO4, in water at 25 °C. Do the calculations in two ways:

1) Use standard enthalpy of formation (ΔH) and entropy (S) from the appendix in your textbook, and use the same formula as you did in the lab experiments: ΔG = ΔH – TΔS. Remember that both ΔH and ΔS has to include three lithium ions.

2) Use standard free energies of formation from Appendix 6 (ΔG) and equation

ΔG = ∑ΔG products – ∑ΔG reactants

Are the results similar in both calculations?

(a) For a process that occurs at constant temperature, does the change in Gibbs free energy depend on changes in the enthalpy and entropy of the system? (b) For a certain process that occurs at constant T and P, the value of ∆G is positive. Is the process spontaneous? (c) If ∆G for a process is large, is the rate at which it occurs fast?