Acid
(noun) A chemical substance that neutralizes alkalis, dissolves some metals, and turns litmus red; typically, a liquid with a pH of less than 7; (adjective) Having the properties of an acid.
Chemically, acids are defined by their ability to donate protons (Brønsted-Lowry) or accept electron pairs (Lewis). Colloquially, it refers to sourness or corrosiveness.
Word relationships
- Sour: Primarily a taste sensation, while 'acid' is a chemical property.
- Corrosive: Describes the destructive property of some acids, but not all acids are highly corrosive.
- Base: A chemical substance that neutralizes acids, accepts protons, and has a pH greater than 7.
- Alkaline: Having the properties of a base; basic.
Commonly confused with
- Base: An 'acid' donates protons and has a pH below 7; a 'base' accepts protons and has a pH above 7.
Word family
- acidic (adjective): Having the properties of an acid; sour.
- acidity (noun): The quality or state of being acidic.
- acidify (verb): To make or become acidic.
Collocations
- strong acid
- weak acid
- amino acid
- fatty acid
- stomach acid
- acid rain
Idioms & expressions
- acid test
Example sentences
- "The sour taste of lemon juice is due to its high concentration of citric acid." Lemon juice is acidic.
- "In a neutralization reaction, an acid reacts with a base to form salt and water." Acids react with bases.
Memory hook
Remember 'acid' sounds like 'add-it' to your tongue and it's sour, or 'acid' is 'a-cid' (a sharp taste). Sour taste
When not to use
Do not use 'acid' to describe something merely sour without the chemical implication; 'sour' is a taste, 'acid' is a chemical property.
Fun facts
- The pH scale, used to measure acidity and basicity, was introduced by Søren Peder Lauritz Sørensen in 1909.
- Hydrochloric acid (HCl) is a strong acid produced naturally in the human stomach to aid digestion.
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