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Our Glaciers: Then and Now activity kit helps you see the changes taking place in glaciers around the world. See all our activity kits and classroom activities.
This drawing represents a comet bringing atmospheric molecules and possibly primitive life forms to the Earth's surface.
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Acids are well known as substances capable of dissolving things. If you've ever gotten some battery acid on your clothes and had a hole develop in a couple weeks you'll know what we mean. In this regard, an acid is very much like a base. Here's a scientific explanation of what an acid is:

An acid is a substance which donates a proton to another species in a reaction. (Donate is really a passive term for what happens. The acid "forces" a proton on a substance which has any capability of accepting it. An acid "donates" a proton the way card players "donate" the Old Maid). Acids are classified as either strong or weak depending upon their relative ability to do this. When it does this, it changes the substance it attacks into a different substance.

There are many acids. Here are a few: Acetic acid (found in viengar), Acetylsalicyclic acid (found in aspirin), Ascorbic acid (found in vitamin C), Citric acid (found in lemon juice), Hydrochloric acid (digestive fluid in the stomach), Sulfuric acid (battery acid). In Earth science however, there only three which really matter because they contribute to weathering of terrestrial rocks. Those are Hydrochloric acid, Sulfuric acid, and Carbonic acid (which plays a role in the Earth's carbon cycle).

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA