chemical equilibrium is like substituting players in a sports game

Categories: Comparisons

An example of a teaching analogy:

"Equilibrium is a situation attained when the rates of forward and reverse reaction are equal, so that there is no change in the concentrations of the reactants and products. Equilibrium can be reached at various points; the concentrations of reactants and products need not be equal, only their rate of exchange. The equilibrium point also shifts in response to stresses placed upon the system.

In a sports game like soccer or basketball, for every new player substituted onto the field, an old player must leave – thus the rate of these opposing reactions are equal. There is no change in the number of players on the field, even though their identities are different. There is no requirement that the number of players on the field and on the bench be equal (and usually they are not equal); the only thing that must be equal is the rate of exchange between these two groups.

In a game like hockey, a penalty would be like a stress … it increases the number of players leaving the ice, compared to the number of players going onto the ice.

At this new equilibrium point the rate of player exchange is again equal for the duration of the penalty. When the penalty is over, the equilibrium point shifts back to the original position."

Previously posted at scienceanalogies.com by retired science teacher Murray Hart – original source: Licata, Kenneth P. Chemistry Is Like A … The Science Teacher 1988, 55(8), 43.

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Many examples of science analogies are listed in 'Creative comparisons: Making science familiar through language. An illustrative catalogue of figurative comparisons and analogies for science concepts'. Free Download.

Author: Keith

Former school and college science teacher, teacher educator, research supervisor, and research methods lecturer. Emeritus Professor of Science Education at the University of Cambridge.