Substances that tend to release hydrogen ions (H⁺) when dissolved in water are called acids. Acids are characterized by their ability to donate protons (hydrogen ions) to other substances. When an acid dissolves in water, it increases the concentration of hydrogen ions in the solution, making the solution acidic.
For example, when hydrochloric acid (HCl) dissolves in water, it dissociates into hydrogen ions (H⁺) and chloride ions (Cl⁻):
HCl → H⁺ + Cl⁻
This release of hydrogen ions is what gives acids their distinctive properties, such as a sour taste, the ability to turn blue litmus paper red, and the ability to react with bases to form salts and water.
Common examples of acids include:
- Hydrochloric acid (HCl)
- Sulfuric acid (H₂SO₄)
- Nitric acid (HNO₃)
- Acetic acid (CH₃COOH)
Understanding acids and their behavior is fundamental in chemistry, as they play a crucial role in various chemical reactions and processes.