Acids and bases affect daily life because they play a role in many reactions, from digesting food to cleaning soap scum off a shower wall. Acids have a pH less than 7.0, while bases have a pH greater than 7.0. Substances with a pH of 7.0 are said to be neutral.
Humans would not be able to digest food without the acid produced by specialized cells in the stomach. The acid breaks down large molecules into smaller ones so that they can be absorbed or eliminated. The blood must also maintain a certain pH for a person to stay healthy. The normal pH of blood is around 7.4, according to the University of Nebraska-Lincoln website.
Sour foods taste that way because of their acidity. Vinegar, oranges and lemon juice are among the many foods with acidic pH levels.
Many of the chemical reactions that occur while cleaning are also the work of acids and bases. Oven cleaners and drain cleaners, among other cleaning products, are bases. Toilet-bowl cleaners are acidic. The acid in these cleaners helps break down mineral deposits.