# equilibrium

## Modeling Dynamic Equilibrium with Coins

This Activity explores factors that influence dynamic equilibrium, including how long it takes two populations to equilibrate, and the relative amounts of reactants and products present at equilibrium. Students first use concrete objects (coins), then progress to mathematical calculations of equilibrium without physically manipulating the objects.

## Liquefaction of Carbon Dioxide - Part 1 of 4

The liquefaction of carbon dioxide is shown. In Part 1, dry ice is placed in a strong plastic tube and a pressure gauge is attached.

## Liquefaction of Carbon Dioxide - Part 2 of 4

The liquefaction of carbon dioxide is shown. In Part 2, the valve is closed and the pressure in the tube builds until all three phases of carbon dioxide are present.

## Liquefaction of Carbon Dioxide - Part 3 of 4

The liquefaction of carbon dioxide is shown. In Part 3, the pressure in the tube continues to rise until the valve is opened, at which point the pressure drops and the liquid changes to solid.

## Liquefaction of Carbon Dioxide - Part 4 of 4

The liquefaction of carbon dioxide is shown. In Part 4, an animation is used to illustrate the correlation between phase and pressure.