Equilibrium and Spontaneity

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Equilibrium and Spontaneity
                                  
                                  
                              
Cathy Little
Jeff Bitton
Jesus Hernandez
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Introduction

• Topics include Equilibrium,Le Chateliers
  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.

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Goals 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 LeChateliers 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 DHo, DSo and DGo.

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Intended Audience

• Second year Honors Chemistry
• Advanced Placement Chemistry
• Advanced Placement Physics B
• Visual Learners

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Placement 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

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Instructional Activities
The unit includes an introduction of topics
through a series of demonstrations/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.

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Instructional Activities

• Demo 3 Detonation of nitrogen triiodide
• Clear illustration of a reaction driven by both
  enthalpic and entropic processes.

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Instructional 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 DHo,
  DSo, DGo.

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Instructional 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 DHo,
  DSo, DGo.

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Samples of Student work
Table I simulation lab
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Samples of Student Work
Table II
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Samples of Student Work
Table III
?G0 -RTLnK or ?G0 ?H0 - T?S0 where
R 1
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Samples of Student Work
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Assessments

• Traditional lab report for the wet lab, graded
  according to rubric.
• Lab report for simulation lab including questions
  embedded within the procedure.
• Homework assignments
• Unit Examination

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The End