Acids

Definition

Acids are substances that can donate a proton (H+) to another substance and typically have a pH less than 7. They are often characterized by their sour taste and ability to turn blue litmus paper red.

5 Must Know Facts For Your Next Test

1. Acids are defined by the Arrhenius, Brønsted-Lowry, and Lewis theories, each providing a different perspective on their behavior.
2. The strength of an acid is determined by its ability to ionize in water; strong acids completely dissociate while weak acids partially dissociate.
3. Common examples of acids include hydrochloric acid (HCl), sulfuric acid (H2SO4), and acetic acid (CH3COOH).
4. In chemical nomenclature, acids containing oxygen are named based on the polyatomic ion they contain; for instance, HNO3 is nitric acid because it contains the nitrate ion.
5. The pH scale is logarithmic, so each whole number change represents a tenfold change in hydrogen ion concentration.

Review Questions

• What defines an acid according to the Brønsted-Lowry theory?
• How does the strength of an acid relate to its degree of ionization in water?
• What is the correct name for H2SO4 using chemical nomenclature?

Related terms

Base: A substance that can accept a proton (H+) or donate an electron pair in reactions. Bases typically have a pH greater than 7.

pH Scale: A scale used to specify how acidic or basic a water-based solution is. It ranges from 0 to 14, with 7 being neutral.

Ionization: The process by which an atom or molecule gains or loses electrons to form ions. In the context of acids, it refers to the dissociation into H+ ions in water.