At room temperature and atmospheric [[pressure]], carbon dioxide is a gas. It becomes solid at -78 °C at standard atmospheric pressure, forming [[dry ice]]. When it thaws, it turns directly into a gas again (called [[sublimation]]).<ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works]</ref> This can be seen from the phase diagram to the right, where at 1 atmosphere of pressure, there is no liquid state separating the solid and gas as temperature rises. | At room temperature and atmospheric [[pressure]], carbon dioxide is a gas. It becomes solid at -78 °C at standard atmospheric pressure, forming [[dry ice]]. When it thaws, it turns directly into a gas again (called [[sublimation]]).<ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works]</ref> This can be seen from the phase diagram to the right, where at 1 atmosphere of pressure, there is no liquid state separating the solid and gas as temperature rises. |