Chemical Equilibrium

A StarLogo Tool for Chemistry Teachers

Team Members

Rey Martinez Janet Penevolpe Deborah Haggerton Jason Goldberg

(here in spirit)

The ProblemThe Problem

How to teach equilibrium with less How to teach equilibrium with less confusion.confusion.

The Problem of EquilibriumThe Problem of Equilibrium

First there must be a reversible First there must be a reversible reactionreaction

Then the “equal” part is the forward Then the “equal” part is the forward reaction rate and the reverse reaction rate and the reverse reaction rate reaction rate

The Problem expandedThe Problem expanded

Le’ Chatelier’s principle states that a Le’ Chatelier’s principle states that a system in equilibrium that is system in equilibrium that is disturbed will counteract that disturbed will counteract that disturbance and establish a new disturbance and establish a new equilibrium. equilibrium.

Literature ResearchLiterature Research

The concept of equilibrium is well The concept of equilibrium is well documented. A plethora of full-text documented. A plethora of full-text articles were found in which chemical articles were found in which chemical equilibrium was of primary focus or equilibrium was of primary focus or in which Le Chatelier's Principle was in which Le Chatelier's Principle was an essential part.an essential part.

Literature ResearchLiterature Research

Le Chatelier's Principle states that, if Le Chatelier's Principle states that, if a closed system at equilibrium is a closed system at equilibrium is subjected to change, processes will subjected to change, processes will occur that tend to counteract that occur that tend to counteract that change.change.

Literature ResearchLiterature Research

According to Sprague, Trey, Pillay & According to Sprague, Trey, Pillay & Khan (2005), Le Chatelier’s Principle Khan (2005), Le Chatelier’s Principle remains to be the most difficult remains to be the most difficult concept for high school students to concept for high school students to comprehend. comprehend.

Literature ResearchLiterature Research

It has been found that students are It has been found that students are able to make observations of able to make observations of chemical processes at the chemical processes at the macroscopic level (e.g., color macroscopic level (e.g., color change) but tend not to be able to change) but tend not to be able to explain explain whywhy these changes occur at these changes occur at the molecular level.the molecular level.

Literature ResearchLiterature Research

An elaborate study by An elaborate study by Azizoglu, Alkan & Geban (2006), Azizoglu, Alkan & Geban (2006), revealed that high school students revealed that high school students may be confused with the concepts may be confused with the concepts because their instructors do not have because their instructors do not have an adequate understanding. an adequate understanding.

Literature ResearchLiterature Research

According to the authors, the two According to the authors, the two most misunderstood concepts in most misunderstood concepts in chemistry are Le Chatelier's principle chemistry are Le Chatelier's principle and the ideal gas lawand the ideal gas law

Literature ResearchLiterature Research

Hanson, from St. Olaf College, suggests Hanson, from St. Olaf College, suggests the use of playing-cards to explore the use of playing-cards to explore statistical aspects of equilibrium (2003)statistical aspects of equilibrium (2003)

While others have posted Web pages While others have posted Web pages featuring conventional definitions, featuring conventional definitions, digital images and practical examples digital images and practical examples using common household items. using common household items.

Literature ResearchLiterature Research

This finding is alarming. This finding is alarming. Consequently, the idea to create a Consequently, the idea to create a

computer simulation that offers computer simulation that offers students an opportunity to students an opportunity to understand unobservable understand unobservable phenomena is the focus of the phenomena is the focus of the project.project.

Literature ResearchLiterature Research

To our knowledge, there are no other To our knowledge, there are no other agent-based models of Le Chatelier’s agent-based models of Le Chatelier’s principle in existence.principle in existence.

ProcedureProcedure

Questions for programmingQuestions for programming

How to model the general reaction ? How to model the general reaction ? A + B A + B C C

How do the reactants disappear?How do the reactants disappear? How to get the product to breakdown? How to get the product to breakdown?

ProcedureProcedure

Agent - Agent interactionsAgent - Agent interactions

Reactant A responds to BReactant A responds to B Reactant B responds to AReactant B responds to A Product C has no responseProduct C has no response

ProcedureProcedure

Agent - Environment interactionsAgent - Environment interactions

There are noneThere are none

Now here’s our modelNow here’s our model

eqdeb05.eqdeb05.slogoslogo

Experiments to analyze output data or use as Demonstrations

Can you find equilibrium:

with only reactants? with only products? faster with double

reactants or products?

Experiments to analyze output data or use as Demonstrations

Le Chatelier

What happens to equilibrium when:

Add A or Subtract A? Add B or Subtract B? Add C or Subtract C? Add A & B or Subtract A & B? Add A & B & C or Subtract all?

Citations

Azizoglu N., Alkan M., & Geban O. (2006). Undergraduate pre-service teachers' understandings and misconceptions of phase equilibrium. Journal of Chemical Education, vol. 83, issue 6, pp. 947-959.

Erickson, F. (1998). Qualitative methods for science education. In B.J. Fraser & K.G. Tobin (ed), International Handbook of Science Education (pp. 1155-1173). Dordretch: Kluwer Academic Publishers.

Citations continued

Hanson, R.M. (2003). Playing-card equilibrium. Journal of Chemical Education. vol.80, issue 11, pg. 1271.

http://www.chemguide.co.uk/physical/equilibria/introduction.html#top

http://www.chm.davidson.edu/java/LeChatelier/LeChatelier.html