Common Student Misconceptions
1. “The world’s supply of oxygen is in danger of being used up.” In fact, if all of the recoverable fossil fuels were burned at one time, the oxygen supply would be reduced only by about 0.05%.
2. “Nitrogen gas and oxygen gas readily react with each other.” The fact that these two gases stay separated in the atmosphere indicates that they are generally unreactive toward each other. In fact, nitrogen reacts with oxygen only at very high temperatures. Lightning is one of the few natural conditions that can generate enough energy for this reaction. The required temperature is also reached in boilers of fossil-fuel plants, automobile engines, jet engines, and large incinerators.
3. “Photosynthesis requires a green plant.” Photosynthesis requires the presence of photosynthetic pigment, chlorophyll, found in green plants, but there are other pigments found in brown plants, red plants, and certain seaweeds that trap wavelengths of light that cannot be absorbed by chlorophyll alone.
4. “Photosynthesis is a simple process.” Although we often show it as a series of 3 or 4 reactions, photosynthesis actually consists of 80-100 different, but interconnected, chemical reactions. Cellular respiration, essentially the reverse of photosynthesis, also consists of around 100 chemical reactions.
5. “Carbon dioxide is the chief absorber of infrared radiation and is mainly responsible for the "Greenhouse effect." Water vapor absorbs infrared radiation over a broader range than CO 2 (see Figure 12), making it the atmospheric constituent most responsible for the “Greenhouse effect.”