Rock bands often use special stage effects, like the fake fog in this picture. Real fog forms when water vapor in the air condenses into tiny droplets of water. The fake fog shown here formed when solid carbon dioxide changed directly to carbon dioxide gas.
Solid carbon dioxide is also called dry ice. That’s because when it gets warmer and changes state, it doesn’t change to a liquid by melting. Instead, it changes directly to a gas without going through the liquid state. The process in which a solid changes directly to a gas is called sublimation. It occurs when energy is added to a solid such as dry ice.
Q: Alyssa’s mom put some mothballs in her closet in the spring to keep moths away from her wool clothes. By autumn, the mothballs were much smaller. What happened to them?
A: Mothballs are made of naphthalene, a substance that undergoes sublimation at room temperature. The solid mothballs slowly changed to a gas during the summer months, explaining why they were much smaller by autumn.
Sublimation of Snow and Ice
Snow and ice may also undergo sublimation under certain conditions. This is most likely to happen where there is intense sunlight, very cold temperatures, and dry winds. These conditions are often found on mountain peaks. As snow sublimates, it gradually shrinks without any runoff of liquid water.
- Sublimation is the process in which a solid changes directly to a gas without going through the liquid state. Solid carbon dioxide is an example of a substance that undergoes sublimation.
- Snow and ice undergo sublimation under certain conditions. This is most likely to happen where there is intense sunlight, very cold temperatures, and dry winds.
- What is sublimation? Give an example.
- Describe conditions under which snow or ice is most likely to undergo sublimation.
- The plastic container pictured in the Figure below is filled with solid air freshener. The solid gradually shrinks after the holes in the top of the container are opened. Explain why this occurs.