1. Liquid Carbon Dioxide Solid carbon dioxide is converted to liquid which quickly converts to gas

2. Purpose  To produce liquid carbon dioxide  To observe rapid phase changes

3. Demonstration  The solid dioxide sublimed to the gaseous form when inside the balloon  The dry ice cooled the gas, under pressure within the balloon, to conditions known as the ‘triple point’  The liquid carbon dioxide rapidly vaporized when poured out of the balloon

4. Concepts 1.Intermolecular Attractions 2.Physical Changes 3.Triple Point

5. 1.Intermolecular Attractions  Attractions between molecules of carbon dioxide keep the substance together in both the liquid and solid state  The intermolecular attractions in carbon dioxide are exceptionally weak  Sublimation is possible because of such weak attractions

6. 2.Physical Changes  Changes in which no new substance is produced  Changes of state  CO 2 (s) CO 2 (l) CO 2 (g) sublimation

7. 3.Triple Point (I)  The temperature and pressure at which the solid, liquid, and gas phases of a substance coexist  For carbon dioxide the triple point occurs at -56.6 degrees Celsius and 5.11 atmospheres of pressure

8. Triple Point (II)  A phase diagram tells what phase a substance will have at a given temperature and pressure Pressure in atm Temperature in degrees Celsius SOLID LIQUID GAS -56.6 degrees 5.11 atm Triple Point

9. Conclusions  Dry ice will normally sublime at room temperature and pressure  Being contained in a balloon increased the pressure and cooled the temperature  Conditions of the triple point were induced within the balloon

10. Comments  Dry ice has a temperature of -78.5 degrees Celsius  When shaken on a cool day the carbon dioxide liquid can be heard sloshing around in a carbon dioxide fire extinguisher