In science, particularly in chemistry, an acid is defined as a substance that can donate a proton (H⁺ ion) to another substance. This definition is part of the Brønsted-Lowry theory of acids and bases. Acids typically have a sour taste, can conduct electricity when dissolved in water, and react with bases to form salts and water.
Acids can also be classified based on their strength:
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Strong Acids: These completely dissociate in water, releasing all their protons. Examples include hydrochloric acid (HCl) and sulfuric acid (H₂SO₄).
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Weak Acids: These partially dissociate in water, resulting in fewer protons being released. Examples include acetic acid (CH₃COOH) and citric acid.
Additionally, acids can be categorized by their origin:
- Inorganic Acids: These are mineral acids such as hydrochloric acid and sulfuric acid.
- Organic Acids: These contain carbon and typically have carboxylic functional groups, such as acetic acid.
Furthermore, in the Lewis definition, acids are characterized as electron pair acceptors. Acids play crucial roles in various chemical reactions, biological processes, and industrial applications.