Acid
- The article about certain properties of databases is at ACID
- Sometimes acid is another name for the drug LSD (Lysergic acid diethylamide)
An acid is something that has a pH less than 7.0 .
Sometimes, the abbreviation HA is used to mean an acid.
The chemistry definition of an acid is: "a substance that donates a hydrogen ion (H+) to another substance, which is called a base. (Or give out hydrogen ions when dissolved in water.)"
Acids can be commonly found in nature. Some of these include:
- Vinegar is probably one of the oldest known acids; it contains acetic acid.
- Nitric acid, NHO3 is known since about the 13th century.
- Citric acids, C6H8O7 can be found in many kinds of fruit. They were probably discovered by Geber in the 8th century.[1][2][3]
- Lactic acid was found by Carl Wilhelm Scheele in 1780. It can be found in sour milk products, such as Yogurt.
- Sulfuric acid, H2SO4 was probably discovered by Geber. Today it can be found in batteries amongst others.
- Hydrochloric acid, HCl
Some acids are strong and others are weak. The weak acids hold on to some of their protons, while the strong acids let go of all of them. Weak acids generally have a pH value of 4-6 while strong acids have a pH value of 1-3.
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[change] Properties
Acids can have different strengths, some are more reactive than others. More reactive acids are often more dangerous.
Acids can have a lot of different properties depending on their molecular structure. Most acids:
- taste sour when they are eaten
- can sting the skin when they are touched
- can corrode (or eat away at) metals and skin
- can be used as a reactant during electrolysis due to the presence of mobile ions
- turn blue litmus paper red
- are studied in chemistry and biology
Acids can burn the skin. The burn can be serious or minor depending on the kind of acid and how concentrated it is. Burns like this can be a serious problem. Chemical burns like this need medical attention immediately.
[change] Importance
Acids are important. Nucleic acids, such as DNA and RNA contain the genetic code. These molecules determine many characteristics of an organism, they are passed from the parents to offspring. DNA contains the plans how to build proteins which are made of amino acids.
Fatty acids and fatty acid derivatives are another group of carboxylic acids that play a significant role in biology. These contain long chains of hydrocarbons and a carboxylic acid group on one end. The cell membrane of nearly all organisms is primarily made up of a phospholipid bilayer, a micelle of hydrophobic fatty acid chains with polar, hydrophilic phosphate "head" groups.
In humans and many other animals, hydrochloric acid is a part of the gastric acid secreted within the stomach. It can help hydrolyze proteins and polysaccharides. It can also convert the inactive pro-enzyme, pepsinogen into the enzyme, pepsin. Some organisms produce acids for defense; for example, ants produce formic acid.
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