This drawing represents a comet bringing atmospheric molecules and possibly primitive life forms to the Earth's surface.
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JPL/NASA
Acid
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 couple of scientific explanations of what an acid is:
An acid is any substance that upon dissolving in water increases the hydrogen content (H+). An acid can also be thought of as 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). 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.
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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