Properties of Gases
10.2 Liquid Nitrogen and Charles’ Law
Subjects: Behavior of gases, ideal gas law, Charles’ Law
Description: Various experiments are performed with liquid nitrogen.
- Small balloons (water balloon size or long narrow balloons)
- Regular size balloon
- Shallow dish (use crystallization dish on prep shelf)
- Liquid nitrogen in a dewar◊
- Insulating gloves
- Tongs for handling balloons
- Small Tupperware container
- Racquet ball (optional)
- Fruit or vegetable to freeze – flower, parsley works well (optional)◊
- Optional: Vernier Thermocouple, interface, and Logger Pro or Logger Lite software.
◊Advanced prep item: Get LN2 ahead of time. Instructor to provide parsley or flower.
*Located in the drawers opposite the bin storage shelves.
- Blow up balloons (at least 5-7) and immerse in liquid nitrogen.
- Blow up regular sized balloon to fit in crystallization dish. You can also use the dewar with the wider mouth for larger balloons.
- Place one last balloon in the dewar with the other balloons.
- Remove all balloons like a magician’s hat and allow to inflate.
- Put the regular balloon in the crystallization dish.
- Pour liquid nitrogen over the balloon. Remove from cold and allow to inflate.
- Place parsley or flower in dewar for ~1 minute.
- Smash on bench top. (Repeat with racquet ball if desired)
- Fill Tupperware half way with liquid nitrogen.
- Cap with lid, Tupperware lid will pop off.
Charles’ Law describes the relationship between temperature and volume. If a given quantity of gas is held at a constant pressure, its volume is directly proportional to temperature. The relationship is given by the equation below:
V = Cc x T
Where Cc is a proportionality constant.
The temperature of liquid nitrogen is 77K (-196°C or -321°F). When an object is immersed in liquid nitrogen, it freezes rapidly and becomes brittle, allowing it to break easily.
When the liquid nitrogen is poured into a container and sealed, the rapid evaporation of the liquid creates a high pressure in the container, causing the lid to pop off.
Liquid nitrogen is extremely cold and can cause hypothermia or burns. Use insulating gloves and safety glasses while performing the demonstration.
1. Prof. Botch
2. Oliver-Hoyo, M., Switzer, W. L. J. Chem. Educ. 2005, 82, 251.
3. NCSU Department of Chemistry Lecture Demonstration website: http://www.ncsu.edu/project/chemistrydemos/DemoList.html
4. University of Illinois at Urbana-Champaign Chemistry department Lecture demonstration web site: http://www.chem.uiuc.edu/clcwebsite/gases.html