Acids are substances that have a pH level below 7. They donate hydrogen ions (H+) when dissolved in water, causing the solution to become acidic. Common examples of acids include hydrochloric acid, sulfuric acid, and nitric acid.
Alkalis (or bases) are substances that have a pH level above 7. They accept hydrogen ions (H+) when dissolved in water, causing the solution to become basic. Common examples of alkalis include sodium hydroxide, potassium hydroxide, and calcium hydroxide.
Neutral substances have a pH level of exactly 7. They neither donate nor accept hydrogen ions when dissolved in water, and therefore do not change the pH of the solution. Common examples of neutral substances include pure water, salt (sodium chloride), and sugar (sucrose).
The pH level of a substance is important in many areas, including chemistry, biology, and medicine. In biological systems, for example, the pH level of body fluids is crucial for maintaining proper cellular function.
