Liquid Carbon Dioxide

Solid carbon dioxide is converted to liquid which quickly converts to gas

Purpose To produce liquid carbon dioxide

To observe rapid phase changes

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

Concepts

1. Intermolecular Attractions

2. Physical Changes

3. Triple Point

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

2. Physical Changes Changes in which no new

substance is produced

Changes of state

CO2(s) CO2(l) CO2(g)

sublimation

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

Triple Point (II) A phase diagram tells what phase a substance will

have at a given temperature and pressure

Pressurein atm

Temperature in degrees Celsius

SOLID

LIQUID

GAS

-56.6 degrees

5.11atm

Triple Point

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

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