What is it?

Definition

An acid is a chemical species that donates protons or hydrogen ions and/or accepts electrons.

Physical Properties

1. pH of less than 7
2. Sharp-tasting or sour
3. Turns litmus paper red
4. Dissolves some metals
5. Neutralizes bases

Acid classification

References

http://www.barransclass.com/phys1090/hw/hwk_14_acid.html

http://chemistry.about.com/od/chemistryglossary/a/aciddefinition.htm