Emerald Robinson: Hi! I am Emerald Robinson and in this What Is video, we are going to discuss the molecule carbon dioxide. Carbon dioxide or CO2 is naturally found in the form of a colorless, odorless gas on earth. It is made of three atoms, one carbon atom and two oxygen atoms. The molecule is held together by covalent bonds, which means electrons are shared between the atoms.
Carbon dioxide makes up 0.39% of our atmosphere and it freezes at about -110 degrees Fahrenheit. Frozen carbon dioxide is commonly called dry ice. Because it takes such a high pressure to turn carbon dioxide into liquid, when dry ice warms up it turns directly from a solid to a gas in a process known as sublimation.
Carbon dioxide is a rich source of the element carbon, the most important building block for life on earth. Green plants use carbon dioxide during photosynthesis. They turn the carbon into the sugar, glucose during a process called fixation. Animals are then able to use this glucose for energy.
Burning fossil fuels like coal, oil, and natural gas releases carbon dioxide into the atmosphere. Over a long period of time, using these fuels has increased the percentage of carbon dioxide in the earth's atmosphere. This higher concentration calls as carbon dioxide to act as a greenhouse gas. Greenhouse gases act like glass in a greenhouse by trapping the heat below the atmosphere. Scientists think greenhouse gases contribute to global warming.
Carbon dioxide is very useful to humans. It is used to extinguish fires and it makes the bubbles in soda and other carbonated drinks. Carbon dioxide from yeast and baking soda makes bakes goods rise and CO2 even makes the holes in Swiss cheese. The right balance of carbon dioxide is imperative to our survival.