Equilibrium and Equilibrium and Spontaneity Spontaneity Cathy Little Jeff Bitton Jesus Hernandez
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Equilibrium and SpontaneityEquilibrium and Spontaneity
Cathy Little Jeff Bitton Jesus Hernandez
IntroductionIntroduction
Topics include Equilibrium,Le Chatelier’s Principle and Gibbs Free Energy.
These topics explain the factors that influence the spontaneity of chemical reactions.
The unit includes demonstrations, a wet lab and a simulation lab.
Goals and ObjectivesGoals and Objectives
Students will be able to determine relationships between equilibrium, thermodynamics and spontaneity– Students will be able to:
Observe the effect of temperature change on the equilibrium according to LeChatelier’s principle.
Determine if the reaction is endothermic or exothermic. Calculate the equilibrium constant at varying temperatures Plot –LnK as a function of 1/T and determine the values of
Ho, So and Go.
Intended AudienceIntended Audience
Second year Honors Chemistry
Advanced Placement Chemistry
Advanced Placement Physics B
Visual Learners
Placement in the CurriculumPlacement in the Curriculum
Second semester AP or Honors Level students
Students should be familiar with
thermochemistry,titrations,solution chemistry,
stoichiometry and kinetics.
The unit can be modified for lower level students
by de-emphasizing quantitative aspects and
emphasizing conceptual features
Instructional ActivitiesInstructional Activities
– Demo 1 – water tank equilibrium This activity models dynamic equilibrium.
– Demo 2 - Cobalt chloride color change This activity illustrates shifts in equilibrium
between different cobalt complexes.
The unit includes an introduction of topics through a series of demonstrations/activities.
Instructional Activities Instructional Activities
Demo 3 – Detonation of nitrogen triiodide– Clear illustration of a reaction driven by both
enthalpic and entropic processes.
Instructional ActivitiesInstructional Activities
Wet laboratory
– Students will determine the Ksp for Borax at various
temperatures using titration and create a graph of
-LnKsp vs. 1/T.
– Students will use the graph to calculate Ho, So, Go.
Instructional ActivitiesInstructional Activities
Simulation Lab
– Students will determine the K for a simulated synthesis
reaction at various temperatures and create a graph of
-LnK vs. 1/T.
– Students will use the graph to calculate Ho, So, Go.
Samples of Student workSamples of Student work
Measurement Temperature # Blue/Purple # Red # Green
1 0.2 460 50 30
2 0.5 320 190 170
3 1 233 277 257
4 1.5 202 308 288
5 2 197 313 293
Table I – simulation lab
Samples of Student WorkSamples of Student Work
Measurement K 1/T LnK1 0.30667 5.0 1.182 0.00991 2.0 4.613 0.00327 1.0 5.724 0.00228 0.7 6.085 0.00215 0.5 6.146 0.00176 0.4 6.34
][*][Re
]/[
Greend
PurpleBlueK
Table II
Samples of Student WorkSamples of Student Work
Measurement Temperature H0 S0 G0
1 0.2 -1.1185 -6.7982 0.23642 0.5 -1.1185 -6.7982 2.30733 1 -1.1185 -6.7982 5.72214 1.5 -1.1185 -6.7982 9.12725 2 -1.1185 -6.7982 12.2866 2.5 -1.1185 -6.7982 15.857
Table III
G0 = -RTLnK or G0 = H0 - TS0 ; where R = 1
Samples of Student WorkSamples of Student Work
-Lnk vs. 1/T -Lnk = -1.1185/T + 6.7982
R2 = 0.9992
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
0.0 1.0 2.0 3.0 4.0 5.0 6.0
1/T
-Ln
k
AssessmentsAssessments
Traditional lab report for the wet lab, graded according to rubric.
Lab report for simulation lab including questions embedded within the procedure.
Homework assignmentsUnit Examination
The End
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